[issue13299] namedtuple row factory for sqlite3
Zaur Shibzukhov added the comment:
Instead of using cache, maybe better to use mutable default argument?
For example:
def make_row_factory(cls_factory, **kw):
def row_factory(cursor, row, cls=[None]):
rf = cls[0]
if rf is None:
fields = [col[0] for col in cursor.description]
cls[0] = cls_factory("Row", fields, **kw)
return cls[0](*row)
return rf(*row)
return row_factory
namedtuple_row_factory = make_row_factory(namedtuple)
Seem it should add less overhead.
--
nosy: +intellimath
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how to make portable distribution of python 2.6?
All greetings! How to make portable distribution of python 2.6? -- http://mail.python.org/mailman/listinfo/python-list
Re: how to make portable distribution of python 2.6?
On 13 авг, 21:28, Thomas Jollans tho...@jollans.com wrote: On 2010-08-13 19:00, zaur wrote: All greetings! How to make portable distribution of python 2.6? I don't know, but what you're looking for probably already exists. Do you mean portable as in portable, i.e. take this and build it for your system, it should work if your OS is supported? Then you can get source tarballs from python.org http://python.org/download/ Or do you understand portable the way that is fashionable in the Windows world nowadays for some reason, i.e. look, Ma, already installed if you happen to use Microsoft Windows of roughly the right version! Thenhttp://www.portablepython.com/is exactly where Google would have lead you had you searched. I want to realize howto build my own portable python in order to use them without installation. I want also to be able install modules (numpy, matplotlib, pyqt, etc...) when it is necessary. This very usefull for teaching python in computer classes. -- http://mail.python.org/mailman/listinfo/python-list
Re: Is behavior of += intentional for int?
On 1 сен, 03:31, Steven D'Aprano st...@remove-this- cybersource.com.au wrote: On Mon, 31 Aug 2009 10:21:22 -0700, zaur wrote: As a result of this debate is not whether we should conclude that there should be two types of integers in python: 1) immutable numbers, which behave as constant value; 2) mutable numbers, which behave as variable value? What can you do with mutable numbers that you can't do with immutable ones, and why do you want to do it? -- Steven Mutable numbers acts as variable quantity. So when augmented assignment is used there is no need to create a new number object in every binary operation. But when I looked now into source of python int (longobject.c) I realized that direct implementation of mutable int will not give any benefit against defining proxy int class, which supports mutability. -- http://mail.python.org/mailman/listinfo/python-list
Re: Is behavior of += intentional for int?
On 29 авг, 16:45, zaur szp...@gmail.com wrote: Python 2.6.2 (r262:71600, Apr 16 2009, 09:17:39) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type copyright, credits or license() for more information. a=1 x=[a] id(a)==id(x[0]) True a+=1 a 2 x[0] 1 I thought that += should only change the value of the int object. But += create new. Is this intentional? As a result of this debate is not whether we should conclude that there should be two types of integers in python: 1) immutable numbers, which behave as constant value; 2) mutable numbers, which behave as variable value? -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 30 авг, 03:22, Gabriel Genellina gagsl-...@yahoo.com.ar wrote: En Sat, 29 Aug 2009 04:34:48 -0300, zaur szp...@gmail.com escribió: On 29 авг, 08:37, Gabriel Genellina gagsl-...@yahoo.com.ar wrote: En Fri, 28 Aug 2009 15:25:55 -0300, zaur szp...@gmail.com escribió: On 28 авг, 16:07, Bruno Desthuilliers bruno. 42.desthuilli...@websiteburo.invalid wrote: zaur a écrit : Ok. Here is a use case: object initialization. Err... Looks like you really should read the FineManual(tm) - specifically, the parts on the __init__ method. What are you doing if 1) classes Person and Address imported from foreign module 2) __init__ method is not defined as you want? Welcome to dynamic languages! It doesn't matter *where* the class was defined. You may add new attributes to the instance (even methods to the class) at any time. [...4 examples...] I know about these ways of object initializing. What I said is about using object's dictionary as nested scope in code block. Object initialization is just one use case. So we say about different things. Well, you asked how to proceed in certain cases and I showed several ways it can be done right now, without requiring a new scope. You'll have to think of another use case. Attribute lookup is explicit in Python, and that's a very good thing. If you follow the python-ideas thread posted earlier, you'll see the kind of problems an implicit attribute lookup would cause. The with statement is necesary (and a good thing) in Pascal, but not in Python. Zope2 departs from this explicitness: it has a dtml-with construct (similar to what you propose), and I hate it profoundly every time I have to edit a DTML file - I can never tell *where* an attribute comes from. Another related feature is acquisition, a stack of namespaces where objects inherit attributes from their containers. Same thing, a complete waste of time every time I have to track a bug. Unless you can find a very compeling use case, I don't think this feature will become part of the language anytime soon... -- Gabriel Genellina The same can be said about multiple inheritance. However, multiple inheritance is a powerful tool in the hands of someone who can properly and effectively use it. -- http://mail.python.org/mailman/listinfo/python-list
Re: Is behavior of += intentional for int?
On 29 авг, 23:03, Steven D'Aprano st...@remove-this- cybersource.com.au wrote: On Sat, 29 Aug 2009 11:11:43 -0700, zaur wrote: I thought that int as object will stay the same object after += but with another integer value. My intuition said me that int object which represent integer value should behave this way. If it did, then you would have this behaviour: n = 3 # bind the name n to the object 3 saved_id = id(n) # get the id of the object n += 1 # add one to the object 3 assert n == 4 # confirm that it has value four assert id(n) == saved_id # confirm that it is the same object m = 3 # bind the name m to the object 3 print m + 1 # but object 3 has been modified 5 This would be pretty disturbing behaviour, and anything but intuitive. Fortunately, Python avoids this behaviour by making ints immutable. You can't change the object 3 to have any other value, it will always have value three, and consequently n+=1 assigns a new object to n. -- Steven This behavior is because small integers are cached internally. See Python 2.6.2 (r262:71600, Apr 16 2009, 09:17:39) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type help, copyright, credits or license for more information. a=1 c=1 d=1 e=1 id(a),id(c),id(d),id(e) (16793992, 16793992, 17067336, 17067276) -- http://mail.python.org/mailman/listinfo/python-list
Re: Is behavior of += intentional for int?
On 30 авг, 15:49, Carl Banks pavlovevide...@gmail.com wrote: I think they (Derek and zaur) expect integer objects to be mutable. It's pretty common for people coming from name is a location in memory languages to have this conception of integers as an intermediate stage of learning Python's object system. Even once they've understood everything is an object and names are references to objects they won't have learned all the nuances of the system, and might still (not unreasonably) think integer objects could be mutable. However, it'd be nice if all these people didn't post here whining about how surprising and unintuitive it is and instead just said, ah, integers are immutable, got it, quietly to themselves. Carl Banks Very expressive. I use python many years. And many years I just took python int as they are. I am also not think about names as reference to objects and so on. So this isn't the case. -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 29 авг, 08:37, Gabriel Genellina gagsl-...@yahoo.com.ar wrote: En Fri, 28 Aug 2009 15:25:55 -0300, zaur szp...@gmail.com escribió: On 28 авг, 16:07, Bruno Desthuilliers bruno. 42.desthuilli...@websiteburo.invalid wrote: zaur a écrit : Ok. Here is a use case: object initialization. For example, person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 vs. person = Person() person.name = john person.age = 30 address = person.address = Address() address.street = Green Street address.no = 12 Err... Looks like you really should read the FineManual(tm) - specifically, the parts on the __init__ method. class Person(object): def __init__(self, name, age, address): self.name = name self.age = age self.address = address class Address(object): def __init__(self, street, no): self.no = no self.street = street person = Person( name=john, age=30, address = Address( street=Green Street, no=12 ) ) What are you doing if 1) classes Person and Address imported from foreign module 2) __init__ method is not defined as you want? Welcome to dynamic languages! It doesn't matter *where* the class was defined. You may add new attributes to the instance (even methods to the class) at any time. 1) person = Person() vars(person).update(name=john,age=30,address=Address()) vars(person.Address).update(street=Green Street,no=12) 2) def the_initializer_i_would_like(person, name, age): person.name = name person.age = age person = Person() the_initializer_i_would_like(person, name=john, age=30) 3) def the_initializer_i_would_like(self, name, age): self.name = name self.age = age Person.init = the_initializer_i_would_like person = Person() person.init(name=john, age=30) 4) def a_generic_updater(obj, **kw): try: ns = vars(obj) except Exception: ns = None if ns is not None: ns.update(kw) else: for name in kw: setattr(obj, name, kw[name]) person = Person() a_generic_updater(person, name=john, age=30) -- Gabriel Genellina I know about these ways of object initializing. What I said is about using object's dictionary as nested scope in code block. Object initialization is just one use case. So we say about different things. -- http://mail.python.org/mailman/listinfo/python-list
Is behavior of += intentional for int?
Python 2.6.2 (r262:71600, Apr 16 2009, 09:17:39) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type copyright, credits or license() for more information. a=1 x=[a] id(a)==id(x[0]) True a+=1 a 2 x[0] 1 I thought that += should only change the value of the int object. But += create new. Is this intentional? -- http://mail.python.org/mailman/listinfo/python-list
Re: Is behavior of += intentional for int?
On 29 авг, 20:25, Günther Dietrich gd_use...@spamfence.net wrote: Paul McGuire pt...@austin.rr.com wrote: What exactly are you trying to do? I think, he wants to kind of dereference the list element. So that he can write a += 1 instead of long_name_of_a_list_which_contains_data[mnemonic_pointer_name] += 1 Regards, Günther That's right. I thought that int as object will stay the same object after += but with another integer value. My intuition said me that int object which represent integer value should behave this way. But by design python's integer behave differently. I fond that NumPy's 1-d types behaves as objects with mutable values. from numpy import * a=array([1]) id(a) 10912544 a += 1 id(a) 10912544 a array([2]) -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 28 авг, 16:07, Bruno Desthuilliers bruno. 42.desthuilli...@websiteburo.invalid wrote: zaur a écrit : On 26 авг, 17:13, Diez B. Roggisch de...@nospam.web.de wrote: Whom am we to judge? Sure if you propose this, you have some usecases in mind - how about you present these Ok. Here is a use case: object initialization. For example, person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 vs. person = Person() person.name = john person.age = 30 address = person.address = Address() address.street = Green Street address.no = 12 Err... Looks like you really should read the FineManual(tm) - specifically, the parts on the __init__ method. class Person(object): def __init__(self, name, age, address): self.name = name self.age = age self.address = address class Address(object): def __init__(self, street, no): self.no = no self.street = street person = Person( name=john, age=30, address = Address( street=Green Street, no=12 ) ) What are you doing if 1) classes Person and Address imported from foreign module 2) __init__ method is not defined as you want? -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 26 авг, 23:56, MRAB pyt...@mrabarnett.plus.com wrote: zaur wrote: On 26 авг, 21:11, Rami Chowdhury rami.chowdh...@gmail.com wrote: person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 Can you clarify what you mean? Would that define a Person class, and an Address class? I suppose that someone already define classes Person ans Address. For example, in this stupid way in a foreign module: class Person(object): pass class Address(object): pass and the following statements person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 are constructing an instance as follows: person = Person() person.name = john person.age = 30 address = person.address = Address() address.street = Green Street address.no = 12 [snip] Create factory functions: def new_address(**kwargs): address = Address() address.__dict__.update(kwargs) return address def new_person(**kwargs): person = Person() person.__dict__.update(kwargs) return person person = new_person(name=john, age=30, address=new_address(street=Green Street, no=12)) Original idea isn't about how to organize my code in order to initialize these custom objects. The idea is about to use object's dictionary as nested scope. -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 27 авг, 18:34, Carl Banks pavlovevide...@gmail.com wrote: On Aug 26, 5:51 am, zaur szp...@gmail.com wrote: Hi folk! What do you think about idea of object's nesting scope in python? Let's imaging this feature, for example, in this syntax: obj=expression: body or expression: body That's means that result object of expression evaluation is used as nested scope for body evaluation. So is this idea useful? It might be marginally useful to save typing. It also allow to structure the code. The idea has been discussed in various forms here quite a bit over the years. I doubt there's any chance it'll be accepted into Python, because it goes against one of the main design points of Python: that attributes should always be accessed explicitly. I don't in general consider this idea as a way for implicit access to object's attributes. Idea is about to use in some way object's dictionary as nested scope in a code block. I agree though that using this only for saving typing or implicit attribute access isn't a good idea. Having said that, the syntax you propose is awful. :) Normally when this is proposed they use a keyword such as using: p = Person() using p: name = Carl Banks location = Los Angeles or, perhaps to save a line (even though it'd be a minor syntax abuse): using Person() as p: name = Carl Banks location = Los Angeles I don't propose concrete syntax for using object's dictionary as nested scope. I used current only to explain the idea. -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 27 авг, 19:19, Carl Banks pavlovevide...@gmail.com wrote: On Aug 27, 8:01 am, zaur szp...@gmail.com wrote: On 27 авг, 18:34, Carl Banks pavlovevide...@gmail.com wrote: The idea has been discussed in various forms here quite a bit over the years. I doubt there's any chance it'll be accepted into Python, because it goes against one of the main design points of Python: that attributes should always be accessed explicitly. I don't in general consider this idea as a way for implicit access to object's attributes. That's what is it regardless of what you consider it. Idea is about to use in some way object's dictionary as nested scope in a code block. Which is implicitly accessing the object's attributes. Carl Banks In my opinion idea of using object's dictionary as nested scope is more about structuring code blocks rather than just saving typing and implicit attribute access. -- http://mail.python.org/mailman/listinfo/python-list
Object's nesting scope
Hi folk! What do you think about idea of object's nesting scope in python? Let's imaging this feature, for example, in this syntax: obj=expression: body or expression: body That's means that result object of expression evaluation is used as nested scope for body evaluation. So is this idea useful? Zaur -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 26 авг, 17:13, Diez B. Roggisch de...@nospam.web.de wrote: Whom am we to judge? Sure if you propose this, you have some usecases in mind - how about you present these Ok. Here is a use case: object initialization. For example, person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 vs. person = Person() person.name = john person.age = 30 address = person.address = Address() address.street = Green Street address.no = 12 In this example any assignment is an equivalence of setting attribute's address of the parent object. -- http://mail.python.org/mailman/listinfo/python-list
Re: Object's nesting scope
On 26 авг, 21:11, Rami Chowdhury rami.chowdh...@gmail.com wrote: person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 Can you clarify what you mean? Would that define a Person class, and an Address class? I suppose that someone already define classes Person ans Address. For example, in this stupid way in a foreign module: class Person(object): pass class Address(object): pass and the following statements person = Person(): name = john age = 30 address = Address(): street = Green Street no = 12 are constructing an instance as follows: person = Person() person.name = john person.age = 30 address = person.address = Address() address.street = Green Street address.no = 12 If you are expecting those classes to be already defined, please bear in mind that if you want, you can do this: class Person(object): def __init__(self, name='Nemo', age=0, address=None): self.name = name self.age = age self.address = address class Address(object): def __init__(self, street=None, no=None): self.street = street self.no = no otherperson = Person( name = 'Bob', age = 26, address = Address( street = 'Blue Street', no = 1 ) ) Yes, that's right. I aware about this way of instance initialization. -- http://mail.python.org/mailman/listinfo/python-list
Python Object Notation (PyON)
Python Object Notation (PyONhttp://code.google.com/p/pyon/wiki/GettingStarted ) Python 2.6/3.0 now has a module ast. This opens up new opportunities. One of them is the possibility of introducing human readable/writable literal object notation, based on the syntax of the python language. I would like to know what do you think about this? Best regards, Zaur -- http://mail.python.org/mailman/listinfo/python-list
[issue4230] __getattr__ can't be a descriptor
zaur [EMAIL PROTECTED] added the comment: It's the issue for python 3.0 too -- nosy: +zaur ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue4230 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
Application of with statement in py3k. Property defining/redefining.
http://szport.blogspot.com/2008/04/application-of-with-statement-in-py3k.html -- http://mail.python.org/mailman/listinfo/python-list
Application of with statement in py3k. Property defining/redefining.
http://szport.blogspot.com/2008/04/application-of-with-statement-in-py3k.html -- http://mail.python.org/mailman/listinfo/python-list
