signature missing in introspection some of the time

[John H Palmieri]

See https://ask.sagemath.org/question/47214/help-doesnt-show-function-call/. Some of the time when you evaluate

   blah?

the signature is not present. Is this a bug or is it intended?

I like this behavior:

sage: A = SteenrodAlgebra()
sage: A.antipode?
Signature:      B.antipode(self, *args)
Call signature: B.antipode(*args)
Type:           ModuleMorphismByLinearity_with_category
String form:    Generic endomorphism of mod 2 Steenrod algebra, milnor basis
File:           ~/Desktop/Sage_stuff/git/sage/local/lib/python2.7/site-packages/sage/modules/with_basis/morphism.py
Docstring:    

   ...

but not this:

sage: mat = random_matrix(ZZ, 3, 3)
sage: mat.add_multiple_of_row?
Docstring:    
   ...

--

John

[Travis Scrimshaw]

Maybe a difference between Python and Cython classes?

Best,

Travis

[Simon King]

On 2019-07-21, Travis Scrimshaw <tsc...@ucdavis.edu> wrote:
> Maybe a difference between Python and Cython classes?

If I recall correctly, Cython can be made to embed information
into the docstring, because otherwise that information wouldn't be
accessible. And with Python classes that information is directly
available from the class, no need to embed the information.

The stuff in sage.misc.sageinspect relies on it (and strips the
embedded information, if I recall correctly, when doing "stuff?").

Best regards,
Simon

[Kwankyu Lee]

There is already a ticket for that:

https://trac.sagemath.org/ticket/26254

but no one is working on it.

[Kwankyu Lee]

Now there is a one-line patch at

https://trac.sagemath.org/ticket/26254

to fix the problem.

I wish that cython experts check that out. I am concerned whether the patch has any unexpected side effect that I cannot foresee.