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Re: Why does dynamic doc string do not work?

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On 21/08/2012 17:44, Miki Tebeka wrote:
> Greetings,
>
>>>> class A:
> ...     '''a doc string'''
> ...
>>>> A.__doc__
> 'a doc string'
>>>> class B:
> ...     '''a {} string'''.format('doc')
> ...
>>>> B.__doc__
>>>>
>
> Is there's a reason for this?
>
> I know I can do:
>>>> class B:
> ...    __doc__ = '''a {} string'''.format('doc')
>
> And it'll work, but I wonder why the first B docstring is empty.
>
I think what's happening is that it's being parsed and then checked to
see whether it's a string literal.

This:

     "doc string"

is OK, as is this:

     "doc" "string"

(implied concatenation) and this:

    ("doc string")

but this isn't:

     "doc" + " string"

because its syntax is:

     ADD(STRING_LITERAL, STRING_LITERAL)

In other words, it's looking at the syntax, not the resulting value.

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Thread

Why does dynamic doc string do not work? Miki Tebeka <miki.tebeka@gmail.com> - 2012-08-21 09:44 -0700
  Re: Why does dynamic doc string do not work? Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-21 11:09 -0600
  Re: Why does dynamic doc string do not work? MRAB <python@mrabarnett.plus.com> - 2012-08-21 18:16 +0100
  Re: Why does dynamic doc string do not work? Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-21 11:21 -0600
  Re: Why does dynamic doc string do not work? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-21 17:22 +0000
  Re: Why does dynamic doc string do not work? Dave Angel <d@davea.name> - 2012-08-21 13:30 -0400
    Re: Why does dynamic doc string do not work? Miki Tebeka <miki.tebeka@gmail.com> - 2012-08-21 10:40 -0700
    Re: Why does dynamic doc string do not work? Miki Tebeka <miki.tebeka@gmail.com> - 2012-08-21 10:40 -0700

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