[Python-ideas] Get the class that *defines* a method

[Amaury Forgeot d'Arc]

Hi,

2013/6/23 anatoly techtonik <techtonik at gmail.com>

> Currently, the only way to get the name of the class that *defines* a
> method is to get chain of parent classes from inspect.getmro() and look
> into every class's dict until a given name is found. Knowing that dict
> contains not only methods, and knowing that it can be modified at run-time,
> this doesn't seem too reliable for me (unless Python itself does the same).
>

Python 3.3 has __qualname__, which may be very useful in your case:
http://docs.python.org/3/whatsnew/3.3.html#pep-3155-qualified-name-for-classes-and-functions

At first I wanted to propose an enhancement to runtime skeleton of Python,
> which is 2D lookup tree for objects and containers that define them. But
> then I realized that it will may not reflect the model I need. For example,
> classes need to provide their parent classes, but in my model classes need
> to provide module name (or function name, or method name) in which they are
> defined.
>
> And while writing this I realized that *definition* scope may be different
> from *run-time* scope, and Python doesn't make it clear:
>
> >>> def lll():
> ...   class A(object):
> ...     pass
> ...   a=A()
> ...   return a
> ...
> >>> lll()
> <__main__.A object at 0x948252c>
> >>> __main__.A
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> NameError: name '__main__' is not defined
>
> The A object is said to be in __main__ namespace, but it seems to be a
> run-time namespace local to function and it seems like Python loses this
> information. There is no information about the function that defined the
> class (owner, parent or .?.), and hence no info about container of the
> function, which makes it hard to assume the scope of variables for this
> class at run-time.
>
>
> So, the above is a generalization of a simple idea - store the "structure
> reference" of the class that *defines* a method inside this method.
> "structure reference" here is the address in the nested scopes formed by
> Python definitions.
>
> The specific action items for you here are:
> 1. is that stuff will be useful (for me it brings some much needed
> consistency into the chaos of run-time Python object space)
> 2. what is the best way to define/cache the reference to the class
> defining the method?
> 3. what is the best way to define/cache the reference to the scope
> defining the method?
> 4. what is the best way to organize storing of this static scope structure
> information at run-time?
>
> See method.im_class note at
> http://docs.python.org/2/library/inspect.html#types-and-members
>
> "Namespaces are one honking great idea -- let's do more of those!" (c)
> import this
> --
> anatoly t.
>
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>
>


-- 
Amaury Forgeot d'Arc
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