[issue18986] Add a case-insensitive case-preserving dict
Changes by Serhiy Storchaka storch...@gmail.com: -- status: open - pending ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: From https://mail.python.org/pipermail/python-dev/2015-May/140003.html == Before the Python 3.5 feature freeze, I should step-up and formally reject PEP 455 for Adding a key-transforming dictionary to collections. I had completed an involved review effort a long time ago and I apologize for the delay in making the pronouncement. What made it a interesting choice from the outset is that the idea of a transformation is an enticing concept that seems full of possibility. I spent a good deal of time exploring what could be done with it but found that it mostly fell short of its promise. There were many issues. Here are some that were at the top: * Most use cases don't need or want the reverse lookup feature (what is wanted is a set of one-way canonicalization functions). Those that do would want to have a choice of what is saved (first stored, last stored, n most recent, a set of all inputs, a list of all inputs, nothing, etc). In database terms, it models a many-to-one table (the canonicalization or transformation function) with the one being a primary key into another possibly surjective table of two columns (the key/value store). A surjection into another surjection isn't inherently reversible in a useful way, nor does it seem to be a common way to model data. * People are creative at coming up with using cases for the TD but then find that the resulting code is less clear, slower, less intuitive, more memory intensive, and harder to debug than just using a plain dict with a function call before the lookup: d[func(key)]. It was challenging to find any existing code that would be made better by the availability of the TD. * The TD seems to be all about combining data scrubbing (case-folding, unicode canonicalization, type-folding, object identity, unit-conversion, or finding a canonical member of an equivalence class) with a mapping (looking-up a value for a given key). Those two operations are conceptually orthogonal. The former doesn't get easier when hidden behind a mapping API and the latter loses the flexibility of choosing your preferred mapping (an ordereddict, a persistentdict, a chainmap, etc) and the flexibility of establishing your own rules for whether and how to do a reverse lookup. Raymond Hettinger P.S. Besides the core conceptual issues listed above, there are a number of smaller issues with the TD that surfaced during design review sessions. In no particular order, here are a few of the observations: * It seems to require above average skill to figure-out what can be used as a transform function. It is more expert-friendly than beginner friendly. It takes a little while to get used to it. It wasn't self-evident that transformations happen both when a key is stored and again when it is looked-up (contrast this with key-functions for sorting which are called at most once per key). * The name, TransformDict, suggests that it might transform the value instead of the key or that it might transform the dictionary into something else. The name TransformDict is so general that it would be hard to discover when faced with a specific problem. The name also limits perception of what could be done with it (i.e. a function that logs accesses but doesn't actually change the key). * The tool doesn't self describe itself well. Looking at the help(), or the __repr__(), or the tooltips did not provide much insight or clarity. The dir() shows many of the _abc implementation details rather than the API itself. * The original key is stored and if you change it, the change isn't stored. The _original dict is private (perhaps to reduce the risk of putting the TD in an inconsistent state) but this limits access to the stored data. * The TD is unsuitable for bijections because the API is inherently biased with a rich group of operators and methods for forward lookup but has only one method for reverse lookup. * The reverse feature is hard to find (getitem vs __getitem__) and its output pair is surprising and a bit awkward to use. It provides only one accessor method rather that the full dict API that would be given by a second dictionary. The API hides the fact that there are two underlying dictionaries. * It was surprising that when d[k] failed, it failed with transformation exception rather than a KeyError, violating the expectations of the calling code (for example, if the transformation function is int(), the call d[12] transforms to d[12] and either succeeds in returning a value or in raising a KeyError, but the call d[12.0] fails with a TypeError). The latter issue limits its substitutability into existing code that expects real mappings and for exposing to end-users as if it were a normal dictionary. * There were other issues with dict invariants as well and
[issue18986] Add a case-insensitive case-preserving dict
Jason R. Coombs added the comment: I'm also eager to hear what limitations prevented the acceptance. Please do link back here when you've posted. I have to say, I'm not entirely surprised. In my implementation, I struggled with some cases, and it certainly doesn't feel like a fully safe implementation. That said, since I mentioned the implementation in jaraco.util earlier, I wanted to announce that those implementations (FoldedCase and FoldedCaseKeyedDict) have been moved to two libraries (jaraco.text and jaraco.collections). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Demian Brecht added the comment: I will be interested to see those reasons. +1. Something like what this PEP proposed would be beneficial in a few places throughout the library (header and cookie implementations would definitely benefit rather than having to deal with buggy normalization themselves). It’s unfortunate that this isn’t going to be approved. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Martin Panter added the comment: I will be interested to see those reasons. Another way to do a similar thing might be using a Key(value, transform) class, somewhat along the lines of Issue 20632, but as a separate class rather than part of the core type system. But I have not thought that idea through very much. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: FYI, the PEP for this isn't going to be accepted (I'm working on the write-up for the reasons why and will post on python-dev). That said, it would be great if the code continues to be improved and then posted on the Python Package Index. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Demian Brecht added the comment: Some refactoring that I'm working on for http.client could use this (currently I have it as part of my patch set). I haven't run into any issues using it and it's definitely useful. Would be nice to get this merged. -- nosy: +demian.brecht ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
STINNER Victor added the comment: The API is simple and well defined, the addition is small, I don't understand what is the problem with this enhancement. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Martin Panter added the comment: For the record, this is related to PEP 455 (key-transforming dictionary) -- nosy: +vadmium ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: 3.5 is almost here; Raymond, care to make a ruling? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: Yes. I intend to button this one up before long. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: [Mark Dickinson] It's essentially an IdentityDict, though I've found other more specific transforms useful. Have any of the applications had use for the part of the API that looks up the original, untransformed key? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Mark Dickinson added the comment: Not my applications, no. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Mark Dickinson added the comment: Mark, what was the use case you found? It's essentially an IdentityDict, though I've found other more specific transforms useful. I was writing a tool to find reference cycles between Python objects (we have a customer application that's working in a multithreaded COM environment and has to ensure that COM objects are released on the same types of threads they were created on, so we have to be careful about cyclic garbage and delayed garbage collection). The graph of Python objects (class 'ObjectGraph') is modelled as a fairly standard directed graph (set of vertices, set of edges, two dictionaries mapping each edge to its head and tail), but of course for this application the dict and set have to be based on object identity rather than normal equality. Using a TransformDict (and an IdentitySet) lets me write the standard graph algorithms (e.g., for finding strongly connected components) in a natural way, leaving it to the TransformDict and IdentitySet to do the necessary id() conversions under the hood.) I also have a similar AnnotatedGraph object (a sort of offline version of the ObjectGraph), where the edges and vertices carry additional information and it's convenient to be able to use a lightweight ID rather than an entire vertex or edge as a dictionary key. Again, using a TransformDict lets one hide the details and present the graph manipulation code readably and naturally. Some code here, if you're interested: https://github.com/mdickinson/refcycle/blob/refactor/refcycle/object_graph.py Caveat: it's work in progress. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Eli Bendersky eli...@gmail.com: -- nosy: -eli.bendersky ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Mark Dickinson added the comment: +1 for this (for Python 3.5, now, I guess). I've just found another place where I'd use it. Looking at the implementation, one thing surprises me a bit: I'd expect the KeyError from a 'del' or 'pop' operation to have the untransformed key rather than the transformed key in its .args. How about '_keys' and '_values' for the slot names, in place of '_original' and '_data'? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: Mark, what was the use case you found? -- versions: +Python 3.5 -Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Antoine, is the PEP ready for review? Well, I think it is. Do you think other points should be addressed in it? We still have some time. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Mark Dickinson dicki...@gmail.com: -- nosy: +mark.dickinson ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: Antoine, is the PEP ready for review? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- assignee: - rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Raymond, have you had time to look at this? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Jason R. Coombs added the comment: I just want to say thanks for working on this. I also have needed this functionality for various needs in the past. To fulfill my needs, I wrote this implementation: https://bitbucket.org/jaraco/jaraco.util/src/1ab3e7061f96bc5e179b6b2c46b06d1c20f87129/jaraco/util/dictlib.py?at=default#cl-221 That implementation is used in the irc library for a case-insensitive dict, but using the IRC-specific standard for case insensitivity (https://bitbucket.org/jaraco/irc/src/1576b10dc2923d4d7234319d2d1e11a5080e1f7d/irc/dict.py?at=default#cl-49). I share this just to add a +1 for the need and to provide additional use cases and implementations for reference. -- nosy: +jason.coombs ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Georg Brandl added the comment: Note that I'm strongly against this name of the getitem() method. -- nosy: +georg.brandl ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Georg Brandl added the comment: Note that I'm strongly against this name of the getitem() method. Any suggestion? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Georg Brandl added the comment: Not really. Would entry be acceptable instead of item? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Georg Brandl added the comment: Not really. Would entry be acceptable instead of item? getentry() sounds decent to me, but it loses the parallel to popitem() and items(). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Georg Brandl added the comment: Hmm, I didn't consider popitem(). Maybe I'm too paranoid about users confusing __getitem__() and getitem() after all :) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: But why not getkey()? Why you need return value too? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: But why not getkey()? Why you need return value too? Because it's more useful to return both. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Sorry, I don't understand why it's more useful. We need create a tuple and then index it or unpack it and drop one of elements. This only muddles away a time and programmer's attention. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: Because most often the time at which you want the original key is the point at which you are about to re-serialize the data...so you need the value too. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: I do think getitem is the most natural name for the method. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eric V. Smith added the comment: On 09/17/2013 09:34 AM, R. David Murray wrote: R. David Murray added the comment: Because most often the time at which you want the original key is the point at which you are about to re-serialize the data...so you need the value too. I can't think of a case where I'd need (original_key, value) where I wouldn't also be iterating over items(). Especially so if I'm serializing. On the other hand, I don't have a use case for the original key, anyway. So I don't have a strong feeling about this, other than it feels odd that the answer to the original question (I think on python-dev) how do we get the original key back? is answered by by giving you the original key and its value. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Oh, could anyone borrow Guido's time machine and rename either __getitem__() to __getvalue__() or items() to entries()? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eric V. Smith added the comment: On 09/17/2013 10:12 AM, Eric V. Smith wrote: On the other hand, I don't have a use case for the original key, anyway. So I don't have a strong feeling about this, other than it feels odd that the answer to the original question (I think on python-dev) how do we get the original key back? is answered by by giving you the original key and its value. I meant: I don't have a use case for finding the original key outside of iterating over items(). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Note: I haven't renamed transformdict to TransformDict yet. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Updated patch adding the getitem() method. -- Added file: http://bugs.python.org/file31757/transformdict2.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Uploading new patch with added transform_func property. -- Added file: http://bugs.python.org/file31761/transformdict3.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Here is an alternative C implementation. It adds to the dict class support of the __transform__() method. If this method is defined in dict subclass it used to transforming keys. collections.TransformDict is just utilizes this feature as collections.defaultdict utilizes __missing__(). This patch changes twice less C code than previous one (227 vs 474 lines). -- Added file: http://bugs.python.org/file31749/dict__transform__.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Does it slow down regular dicts? I were surprized, but yes. The ComplexPythonFunctionCalls test from pybench is 40% slower with ctransformdict.patch (and I still don't known why). With dict__transform__.patch it is only 2% slower. All other pybench tests are approximately equal. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Does it slow down regular dicts? I were surprized, but yes. The ComplexPythonFunctionCalls test from pybench is 40% slower with ctransformdict.patch (and I still don't known why). With dict__transform__.patch it is only 2% slower. All other pybench tests are approximately equal. Did you try any other microbenchmarks? Your approach sounds promising. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Did you try any other microbenchmarks? Your approach sounds promising. Any microbenchmarks which I tried did not show any interesting. Until I found the cause of slowing down ComplexPythonFunctionCalls I have no idea which tests can be representable. Of course you can run benchmarks yourself. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Serhiy, any benchmarks for your implementation? Does it slow down regular dicts? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: On 09/11/2013 02:39 PM, Tim Delaney wrote on PyDev: I would think that retrieving the keys from the dict would return the transformed keys (I'd call them canonical keys). The more I think about this the more I agree. A canonicaldict with a key function that simply stored the transformed key and it's value would seem to be a lot simpler: - no need to store a separate presentation key - no confusion about which of the first key/last key seen is stored - no mistakes with the first key not being added before real data and getting the presentation key wrong Further, in order to store the non-canonical keys a separate list must be kept of the keys to preseed the canonicaldict; if we store the canonical keys a separate list must be kept for presentation purposes -- so worst case scenario we're keeping the same amount of information and best-case scenario the presentation of the keys doesn't matter and we just saved ourselves an extra data structure. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: True, but how big a deal is that? For one, it seems questionable to have the presentation portion of the data be part of the key. For two, when presentation is important a separate list must be kept anyway to preseed the dict; so just use that list to cycle through the canonicaldict: -- some_dict = some_function_that_returns_a_conanicaldict() -- presentation_list = ['IBM','Intel','AMD'] -- for company in presentation_list: ... key = some_dict.key[company] # demo purposes only ... value = some_dict[company] ... print(key, company, value) ibm IBM 2172 intel Intel 3210 amd AMD 4399 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: It would be simpler, but it would also be useless for the actual use case for which this issue was opened. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: R. David Murray added the comment: You are conceptualizing this very differently. In our view, this data structure is for cases where the original key is the most important piece of information (about the keys). The transformation in the lookup process is entirely in the service of looking up the value paired with that original key when there is more than one possible representation of that key. It is the original key that is critical when re-serializing the data or otherwise making use of the keys for anything other than lookup. So this is about making the data structure succinctly model the problem domain, which is what OO is supposed to be good at :) Thanks for putting it much more convincingly than my python-dev response :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Ethan, please don't post the same message *both* on the tracker and on the mailing-list. I'm sure most people here also read the ML thread. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: You are conceptualizing this very differently. In our view, this data structure is for cases where the original key is the most important piece of information (about the keys). The transformation in the lookup process is entirely in the service of looking up the value paired with that original key when there is more than one possible representation of that key. It is the original key that is critical when re-serializing the data or otherwise making use of the keys for anything other than lookup. So this is about making the data structure succinctly model the problem domain, which is what OO is supposed to be good at :) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: Right, sorry. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Here is a preliminary C implementation. -- Added file: http://bugs.python.org/file31728/ctransformdict.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Serhiy Storchaka storch...@gmail.com: Removed file: http://bugs.python.org/file31728/ctransformdict.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Serhiy Storchaka storch...@gmail.com: Added file: http://bugs.python.org/file31729/ctransformdict.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: (now relayed on python-dev) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: I'm uploading a pure Python transformdict implementation + tests, for Serhiy's benefits (and others') :-) -- keywords: +patch Added file: http://bugs.python.org/file31713/transform.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Richard Oudkerk added the comment:
With the current patch __repr__() will fail if the untransformed key is
unhashable:
d = collections.transformdict(id)
L = [1,2,3]
d[L] = None
d.keys()
Traceback (most recent call last):
File stdin, line 1, in module
File C:\Repos\cpython-dirty\lib\collections\abc.py, line 444, in __repr__
return '{0.__class__.__name__}({0._mapping!r})'.format(self)
File C:\Repos\cpython-dirty\lib\collections\__init__.py, line 944, in
__repr__
self._transform, repr(dict(self)))
TypeError: unhashable type: 'list'
--
nosy: +sbt
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[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: With the current patch __repr__() will fail if the untransformed key is unhashable: Yeah, the __repr__() implementation will be a bit annoying to get right :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Éric Araujo added the comment: FTR this is one message from the previous thread about this: https://mail.python.org/pipermail/python-ideas/2010-June/007332.html -- nosy: +eric.araujo ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Updated patch: fixes repr(), and retains the first key not the last. -- Added file: http://bugs.python.org/file31727/transformdict.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Arfrever Frehtes Taifersar Arahesis arfrever@gmail.com: -- nosy: +Arfrever ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Raymond Hettinger added the comment: I would *really* like for this to start outside the standard library. It needs to mature with user feedback before being dumped in the collections module (which was never intended to be a giant pile of every collection a person could think of). Adding yet more dictionary variants is an example of way-too-many-ways-to-do-it. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
New submission from Antoine Pitrou: This is a very common need when implementing network protocols. You want to match keys case-insensitively but also preserve the original casing (e.g. for presentation). When searching on the Web, you see many people reimplementing their own variant (often incomplete, or buggy). For example, Twisted has its own, the email package has something resembling it, WebOb also. Having an implementation in the stdlib would spare many people the effort, ensure the implementation is complete and well-tested, and perhaps also add some optimizations to mitigate the overhead compared to a plain dict. Note this is an instance of a more general pattern, where they key used for matching is derived from the lookup key using a constant derivation function. So maybe we want to implement the more general pattern and let users specify str.lower as the key derivation function. -- components: Library (Lib) messages: 197359 nosy: barry, pitrou, r.david.murray, rhettinger, tim.peters priority: normal severity: normal status: open title: Add a case-insensitive case-preserving dict type: enhancement versions: Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Thomas Heller thel...@ctypes.org: -- nosy: +theller ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Matthew Barnett added the comment: Surely a case-insensitive dict should use str.casefold, not str.lower? -- nosy: +mrabarnett ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Surely a case-insensitive dict should use str.casefold, not str.lower? Perhaps. Network protocols will usually only allow ASCII in parts where case is insensitive (e.g. header names), so it shouldn't make a difference. Implementing the generic pattern means this is left at the user's discretion, though. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: For the record, I have my own implementation here: https://bitbucket.org/optiflowsrd/obelus/src/tip/obelus/casedict.py?at=default https://bitbucket.org/optiflowsrd/obelus/src/tip/obelus/test/test_casedict.py?at=default -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Changes by Ethan Furman et...@stoneleaf.us: -- nosy: +ethan.furman ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: For the record, email is not a good argument for this, since email could not use this data structure (its data structure is *not* a dict, but a list with dict-like features grafted on). I do think this would be useful, and the generic version (analogous to defaultdict) would seem to make sense. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Ok, let's bikeshed this a bit. What should be the name? - projectdict? - normalizedict? - normdict? - derivedict? - transformdict? - any ideas? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: I would say - transformkeydict Too bad we can't just add an extra 'transform_key' keyword to defaultdict. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eric V. Smith added the comment: It would be nice to combine the behaviors that defaultdict and the case-insensitive comparisons. -- nosy: +eric.smith ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eric V. Smith added the comment: Just today I was using a defaultdict where the keys are stock symbols. They're case insensitive (at least for this particular application). In this case I just str.upper everything, but it would be a nice feature to case-preserve the keys that I pre-populate. I care less about the keys from user data. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: In this case I just str.upper everything, but it would be a nice feature to case-preserve the keys that I pre-populate. I care less about the keys from user data. Well, stock symbols are what I would call user data :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eric V. Smith added the comment: True enough! I was trying to distinguish keys that I populate with initial values (mostly stock indexes) versus those where I just read values from a user-supplied file. When I populate the index values, I'd like to preserve the case I initially used. When I use user-supplied values, I don't know that the first value I use to populate the defaultdict has any more meaning that the last one I see. It would just be a nice-to-have feature for which I have a real use case. It's not so critical that I can't work around it. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: It would be nice to combine the behaviors that defaultdict and the case-insensitive comparisons. Any use case? In my experience they are used in completely different situations. defaultdict mostly to use the writing of some (internal) algorithms, a case-insensitive dict to store user-visible data. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: To the point, however, Eric's example would make use of both the defaultdict portion and the transformkey portion in a single dict. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Matthew Barnett added the comment: mappeddict? Re defaultdict, you could write a dict that does all of these things, called superdict! :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: coercekeydict -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: I would like to shorten the proposals to transformdict and coercedict. (after all, transforming the values would have little sense: you can do it yourself trivially) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
STINNER Victor added the comment: FYI os.environ uses something similar: keys and values are encoded and decoded using functions. So any transformation is supported. http://hg.python.org/cpython/file/eac63e7ceb03/Lib/os.py#l636 On UNIX, the encoder and decoder are os.fsencode() and os.fsdecode() (not exactly, the real functions are more strict on the input type). On Windows, the encoder converts the key to uppercase. -- nosy: +haypo ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Eli Bendersky added the comment: +1 For the general idea +1 For the more generic approach of which lowercase is just one special case +10 to make this a PEP so that more people have a chance to express their opinion (currently only those who noticed it on the issues mailing list). I find the issue tracker a very bad medium for any kind of brain-storming or bikeshedding. -- nosy: +eli.bendersky ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: FYI os.environ uses something similar: keys and values are encoded and decoded using functions. So any transformation is supported. I don't think this is the same situation. os.environ has bijective transformations, which don't pose any implementation challenge. The whole point of a transformdict is to allow for multiple keys to actually map to the same dict entry. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: +10 to make this a PEP so that more people have a chance to express their opinion (currently only those who noticed it on the issues mailing list). I find the issue tracker a very bad medium for any kind of brain-storming or bikeshedding. Well, I don't think there is a lot of brainstorming to be done here: we are talking about a single well-defined functionality. I don't mind writing a PEP if other people ask for it, but I'd rather spend my time on more important things. As for bikeshedding, there is no good medium for it, really :-) At worse we could ask python-dev for their naming contributions (a great idea, surely). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: See also discussion on a topic: http://comments.gmane.org/gmane.comp.python.ideas/18469 . Proposed names: custom_dict, KeyedDictionary, Dictionary. It will be confused if this dict will not be compatible with PyDict API. It is possible to add such feature directly into the dict class (I experimented with IdentityDict). -- nosy: +serhiy.storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
R. David Murray added the comment: Indeed. Although there was apparently some call for it, it doesn't sound from a quick google like defaultdict was deemed to require a PEP. Presumably the informed audience should be wider than this issue, though. I also note that defaultdict is implemented via a special method on dict itself (__missing__), and if this one was implemented the same way it would be easy to combine the features. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Ethan Furman added the comment: Precisely what I was thinking. :) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: I also note that defaultdict is implemented via a special method on dict itself (__missing__), and if this one was implemented the same way it would be easy to combine the features. It's not that simple: to remember the original casing you need either a second container, or to use (original_key, value) tuples as values. Both approaches have non-trivial repercussions on the implementation of many methods. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: (as a sidenote, you might want a case-insensitive OrderedDict as well, I see no reason to make a special case for defaultdict here) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: Proposed names: custom_dict, KeyedDictionary, Dictionary. Sounds much too vague and un-specific. It will be confused if this dict will not be compatible with PyDict API. Why? Many custom dict-like classes aren't. It is possible to add such feature directly into the dict class (I experimented with IdentityDict). Can you explain how? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: Why? Many custom dict-like classes aren't. And this is weird (issue10977). Can you explain how? By patching Objects/dictobject.c of course. I suppose it should require changing about 400 lines of code, a little more than for IdentityDict. When you provides the specification perhaps I will provide a patch. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: By patching Objects/dictobject.c of course. Am I stupid :-) I suppose it should require changing about 400 lines of code, a little more than for IdentityDict. When you provides the specification perhaps I will provide a patch. Well, take a look at the code I've pointed to above. I'm curious to know how you'll integrate it in dictobject.c without slowing down normal dict objects, and without making them bigger. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Serhiy Storchaka added the comment: I'm curious to know how you'll integrate it in dictobject.c without slowing down normal dict objects, and without making them bigger. It of course will make a size of source file bigger, but shouldn't affect a size or performance of normal dicts. A dict object contains dk_lookup. Constructor for keyed dict (subclass of ) should initialize it with specialized function which calls the key function and recalculate a hash (yes, with this simple approach a hash will be calculated twice, for original and for transformed keys). Hmm, actually it can be even simpler than for IdentityDict (for which not calculating a hash was important). Also some other methods which relies on dict implementation details (e.g. making a copy of dict) should be modified. The most cumbersome part is the tests. Unfortunately I lost my tests for IdentityDict (used hg diff without --git). It will be good if your provide complete test suite. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: It of course will make a size of source file bigger, but shouldn't affect a size or performance of normal dicts. A dict object contains dk_lookup. You need to keep both the original keys and the transformed keys. It's not only about transforming keys on lookup. Otherwise, yes, it's trivial. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18986] Add a case-insensitive case-preserving dict
Antoine Pitrou added the comment: It will be good if your provide complete test suite. ... Again, take a look at the code I've posted above ... -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18986 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
