Inherit Method but keep Documentation?

[Michael Jung]

Dear developers,

to reduce redundancies in the SageManifolds code, we plan to inherit most methods and classes from a (mathematically) more general setup.

Still, the current documentation is mandatory. Is it possible to establish new documentations for inherited methods?

An example:

class Mother(SageObject):
    def my_method(self):
        r"""
        Some Documentation.
        """"
        return 'Bam!'

class Daughter(Mother):
    pass

For the class "Daughter", the method "my_method" shall have a separate self-containing documentation.

Best regards
Michael

[Michael Orlitzky]

On 3/18/20 5:04 PM, Michael Jung wrote:
> Dear developers,
> to reduce redundancies in the SageManifolds code, we plan to inherit
> most methods and classes from a (mathematically) more general setup.
> Still, the current documentation is mandatory. Is it possible to
> establish new documentations for inherited methods?

I tried, and I don't think so.

If you don't override the method, then the subclass method will
literally point to the superclass method, implying that they both have
to have the same __doc__.

[Michael Jung]

Damn it. Then I another question: Would it cause a slow-down if I overwrite the method with something like

def my_method(self):
    r"""
    New Documentation
    """
    Mother.my_method(self)

Best,
Michael

Virenfrei. www.avast.com

[David Roe]

On Wed, Mar 18, 2020 at 10:58 PM Michael Jung <mic...@uni-potsdam.de> wrote:

Damn it. Then I another question: Would it cause a slow-down if I overwrite the method with something like

def my_method(self):
    r"""
    New Documentation
    """
    Mother.my_method(self)

This will take small amount of time (on the order of 150ns), but that time will probably be dwarfed by whatever Mother.my_method is doing.  I don't see an alternative if you want to have different documentation.

David

Best,
Michael

Am 19.03.2020 um 00:41 schrieb Michael Orlitzky:

On 3/18/20 5:04 PM, Michael Jung wrote:

Dear developers,
to reduce redundancies in the SageManifolds code, we plan to inherit
most methods and classes from a (mathematically) more general setup.
Still, the current documentation is mandatory. Is it possible to
establish new documentations for inherited methods?

I tried, and I don't think so.

If you don't override the method, then the subclass method will
literally point to the superclass method, implying that they both have
to have the same __doc__.

Virenfrei. www.avast.com

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[John H Palmieri]

What about

my_method = Mother.my_method
my_method.__doc__ = "new docstring"

Does that do what you want?

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[Simon King]

Hi!

On 2020-03-19, John H Palmieri <jhpalm...@gmail.com> wrote:
> What about
>
> my_method = Mother.my_method
> my_method.__doc__ = "new docstring"
>
>
> Does that do what you want?

Probably not. Wouldn't that be the same as
Mother.my_method.__doc__ = "new docstring"
?

Best regards,
Simon

[Michael Orlitzky]

On 3/19/20 3:47 AM, Simon King wrote:
>
> Probably not. Wouldn't that be the same as
> Mother.my_method.__doc__ = "new docstring"
> ?
>

Yeah, that's what I tried, and it overwrites the parent method's docstring.

[Simon King]

Hi Michael,

perhaps the code in src/sage/docs/instancedoc.pyx is helpful for you?

I see several problems:
1. It is possible to override the __doc__ of an anbound method, but this
would override the __doc__ also in the parent class:

sage: class A:
....: def my_method(self):
....: "Some doc"
....: pass
....:
sage: class B(A): pass
sage: B.my_method.__doc__ = "Some other doc"
sage: A.my_method.__doc__
'Some other doc'

2. It is impossible (without Cython, at least) to override the __doc__
of a bound method:

sage: a = A()
sage: a.my_method.__doc__ = "Some more doc"
...
AttributeError: attribute '__doc__' of 'method' objects is not writable

3. I thought a potential solution would be to create a subclass
FlexibleDocMethodType of types.MethodType that uses the instancedoc
decorator, say by accessing some attribute of the_method.__self__ that
holds the new doc. "Usual" methods would then (via some decorator) be
replaced by instances of FlexibleDocMethodType. But unfortunately it
seems that types.MethodTypes cannot be subclassed:

sage: from types import MethodType
sage: class FlexibleDocMethodType(MethodType):
....: pass
....:
...
TypeError: type 'method' is not an acceptable base type

Best regards,
Simon

[Nils Bruin]

There is a way of "copying" a function object, so that you can change the documentation on it.

You should just not do it because it's horribly hacky.

def f(a):
    "doc of f"
    return 0

import types
g=types.FunctionType(f.__code__,f.__globals__)
g.__doc__="doc of g"

g.__doc__
f.__doc__

I think the original doc is actually stored on the __code__ object, so you could also copy that and change the docstring there, but the override on functions seems to work OK. types.CodeType could be employed for that probably.