[Patches] [ python-Patches-550290 ] doc strings of builtin types

Tue, 21 May 2002 12:39:55 -0700

Patches item #550290, was opened at 2002-04-29 13:58
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http://sourceforge.net/tracker/?func=detail&atid=305470&aid=550290&group_id=5470

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Thomas Heller (theller)
Assigned to: Nobody/Anonymous (nobody)
Summary: __doc__ strings of builtin types

Initial Comment:
pydoc creates a strange description for the __doc__
member: it prints the doc-string of 'str'. Example:

C:\>c:\sf\python\dist\src\PCBuild\python.exe
Python 2.3a0 (#29, Apr 15 2002, 18:33:31) [MSC 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for
more information.
>>> class O(object):
...   "some text"
...
>>> import pydoc
>>> pydoc.help(O)
Help on class O in module __main__:

class O(__builtin__.object)
 |  some text
 |
 |  Data and non-method functions defined here:
 |
 |  __dict__ = <dict-proxy object at 0x0080D410>
 |
 |  __doc__ = 'some text'
 |      str(object) -> string
 |
 |      Return a nice string representation of the object.
 |      If the argument is a string, the return value
is the same object.
 |

The attached patch prints the following (also for the
HTML output):
 |  __doc__ = 'some text'
 |      The documentation string
 |

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>Comment By: Guido van Rossum (gvanrossum)
Date: 2002-05-21 15:39

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> Hm, I see no pydoc2.diff ;-)

Oops, here's pydoc2.diff

> IMO, pydoc should try to document the _purpose_ of the
> special attributes (__doc__, __module__, ...) instead
> of their _value_.

Maybe, but aren't there lots of these?  Maybe this ought to
be table-driven instead of an if-statement for each one.
I'll call YAGNI on this one for now; at best it's a separate
feature request.

> > For the other issue, I'm not sure *what* to do. Tim
suggests
> > that perhaps for the basic types, x.__doc__ should
return
> > None. Opinions?
> That's what my sample patch stringobject.diff does.
> +1 from me.

That's what I realized after looking at your string patch.
:-)

Raymond, do you want to work on finishing this?

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Comment By: Thomas Heller (theller)
Date: 2002-05-21 15:24

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> I think there are actually two issues here: pydoc shows the
> docstrings for what it calls "data and non-method
> functions", which usually aren't helpful; and the docstrings
> for basic types are confusing when retrieved through an
> instance.
> 
> For the pydoc issue, I have a different patch
> (pydoc2.diff).  This suppresses the docstring completely
> unless the value is callable. (Now, I know that callable()
> is not 100% reliable, but it's close enough for pydoc.)
Hm, I see no pydoc2.diff ;-)
IMO, pydoc should try to document the _purpose_ of the
special attributes (__doc__, __module__, ...) instead
of their _value_. 

> For the other issue, I'm not sure *what* to do. Tim suggests
> that perhaps for the basic types, x.__doc__ should return
> None. Opinions?
That's what my sample patch stringobject.diff does.
+1 from me.

----------------------------------------------------------------------

Comment By: Guido van Rossum (gvanrossum)
Date: 2002-05-21 15:13

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I think there are actually two issues here: pydoc shows the
docstrings for what it calls "data and non-method
functions", which usually aren't helpful; and the docstrings
for basic types are confusing when retrieved through an
instance.

For the pydoc issue, I have a different patch
(pydoc2.diff).  This suppresses the docstring completely
unless the value is callable. (Now, I know that callable()
is not 100% reliable, but it's close enough for pydoc.)

For the other issue, I'm not sure *what* to do. Tim suggests
that perhaps for the basic types, x.__doc__ should return
None. Opinions?

----------------------------------------------------------------------

Comment By: Guido van Rossum (gvanrossum)
Date: 2002-05-16 08:36

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I'm very sympathetic, but have no time to review this just
yet. Please don't check in without my approval -- this is
awfully deep shit (see the history of the __doc__ descriptor
in typeobject.c).

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Comment By: Raymond Hettinger (rhettinger)
Date: 2002-05-15 11:13

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Since this would also go into int, float, and other places, 
consider factoring it to abstract.c as 
PyObject_GenericGetNoneDoc or some such.

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Comment By: Thomas Heller (theller)
Date: 2002-05-15 08:51

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The attatched patch (stringobject.diff) implements this
behaviour: The doc string of 'str' is unchanged, but string
objects have a __doc__ attribute of None.
The same could (and should) be done for int, float, and
probably more types as well.

----------------------------------------------------------------------

Comment By: Thomas Heller (theller)
Date: 2002-05-07 13:08

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Or maybe add a __doc__ tp_member (or whatever) which always 
returns None?

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Comment By: Thomas Heller (theller)
Date: 2002-05-07 13:06

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No, I cannot think of a better wording.
The problem (as you know) is that we have to cover three 
cases: the str() function, the str type, and the string 
instances (same for all the other 'simple' types).
Would it be worth to add a _doc field to the PyStringObject 
structure and add a __doc__ entry to tp_members?

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Comment By: Guido van Rossum (gvanrossum)
Date: 2002-05-07 08:34

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The instance doc is supposed to be the same as the class
doc, yes.

I suppose the str() __doc__ is not particularly appropriate
for string instances.

Can you suggest a better wording? (This problem is
widespread, I presume, so a generic solution may be in
order.)

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Comment By: Thomas Heller (theller)
Date: 2002-04-30 10:50

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Please ignore my previous comments.

It turns out that the problem is not in pydoc, it is in
Python itself. "spam".__doc__ is the same as str.__doc__
(which describes what the callable 'str' does.
Is this intended?

The side-effect is that pydoc prints unexpected output for
class variables. Execute this code to find out:

class X:
    a = "a string"
    b = 42

import pydoc
pydoc.help(X)

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Comment By: Thomas Heller (theller)
Date: 2002-04-30 10:49

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Please ignore my previous comments.

It turns out that the problem is not in pydoc, it is in
Python itself. "spam".__doc__ is the same as str.__doc__
(which describes what the callable 'str' does.
Is this intended?

The side-effect is that pydoc prints unexpected output for
class variables. Execute this code to find out:

class X:
    a = "a string"
    b = 42

import pydoc
pydoc.help(X)

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Comment By: Thomas Heller (theller)
Date: 2002-04-30 04:24

Message:
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The same problem exists for the __module__ attribute. I can
update the patch if needed.

----------------------------------------------------------------------

You can respond by visiting: 
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[Patches] [ python-Patches-550290 ] __doc__ strings of builtin types

[Patches] [ python-Patches-550290 ] doc strings of builtin types