On 2020-02-18 6:04 p.m., Chris Angelico wrote:
Too short, didn't read. Specifically, I'm not going to go digging
through your links to find code to justify why you want this feature.
Post some code here, or at very least, link directly to the code that
would be improved by this feature.
Soni, you're very close to my mental blocklist. Please put a bit more
effort into your posts to make it clear what you're actually
proposing, rather than making each of us do the work.
ChrisA
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Alright, sorry.
The documentation states:
"ABDL expressions are regex-like constructs for matching and validating
object structures. They can be used with JSON and similar formats, and
even self-referential data structures."
"ABDL expressions have the ability to iterate, index, validate and
filter data structures, through the use of the syntax elements below."
"An arrow is ``->`` and indicates indexing/iteration (Mappings,
Sequences, Sets). Whether indexing or iteration is used is defined by
the elements that follow, with iteration being used by default."
"A variable is a sequence of alphanumeric characters, not starting with
a digit. A ``(key, value)`` tuple containing the respective matched
element will be identified by this name in the results dict."
And this sums up the core aspect of the library: the library is built on
the idea of iterating "canonical keys" and their corresponding values,
and validating and filtering them. ("[...] iteration being used by
default", meaning indexing takes additional syntax - this is unlike some
JSON and XML query languages where indexing takes /less/ syntax and
filtering is generally highly limited and verbose.)
Iteration is done thusly:
def _pairs(obj):
if isinstance(obj, collections.abc.Mapping):
return iter(obj.items())
elif isinstance(obj, collections.abc.Sequence):
return iter(enumerate(obj, 0))
elif isinstance(obj, collections.abc.Set):
return iter(((e, e) for e in obj))
else:
# maybe there's more stuff I can implement later
raise TypeError
I think having a proper protocol for this behaviour would be beneficial,
as no (monkey)patching would be needed to add support for additional
collections and data types. The comment saying there may be additional
data types I've missed would then become irrelevant, as they'd be
covered by __valid_getitem_requests__.
Sometimes you just want to treat everything as a (read-only) dict.
Mostly when dealing with user input (e.g. configs), but not only.
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