[debbugs-tracker] bug#10163: closed (Incomplete/vague section of Guile Manual)

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Your message dated Thu, 22 Dec 2011 09:34:28 -0500
with message-id <address@hidden>
and subject line Re: bug#10163: Incomplete/vague section of Guile Manual
has caused the debbugs.gnu.org bug report #10163,
regarding Incomplete/vague section of Guile Manual
to be marked as done.

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10163: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10163
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--- Begin Message --- Subject: Incomplete/vague section of Guile Manual Date: Tue, 29 Nov 2011 20:17:18 -0500 Hello,
In section 5.7.1.4, "Writing Guile Primitives for Dia" at http://www.gnu.org/software/guile/manual/guile.html, the description of the square_p() implementation is incomplete. It uses a macro call to ensure that the SCM value is a shape, but does not explain what that implementation is:

/* Check that arg is really a shape SMOB. */
SCM_VALIDATE_SHAPE (SCM_ARG1, shape);

The explanation merely states:
"SCM_VALIDATE_SHAPE is a macro that you should define as part of your SMOB definition: it checks that the passed parameter is of the expected type."

After some searching, I was able to figure out that the function scm_assert_smob_type() is probably the intended behaviour for this. However, there was no indication of this in the description.

As a side note: I'm a new Schemer, so perhaps this isn't idiomatic, but would it make more sense to use the SCM_SMOB_PREDICATE macro instead? This way, you can simply return false for any type, even if it isn't a shape. Asking if a number is a shape (for example) doesn't strike me as particularly exceptional or incorrect.

Thanks,

Ryan Fox

--- End Message ---

> --- Begin Message ---
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> Subject: 
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> Re: bug#10163: Incomplete/vague section of Guile Manual
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>
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>
> Date: 
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> Thu, 22 Dec 2011 09:34:28 -0500
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>
> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux)
>
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>
> Hi Ryan,
>
> Thanks for the report.
>
> On Tue 29 Nov 2011 20:17, Ryan Fox <address@hidden> writes:
>
> > /* Check that arg is really a shape SMOB. */
> > SCM_VALIDATE_SHAPE (SCM_ARG1, shape);
> >
> > After some searching, I was able to figure out that the
> > function scm_assert_smob_type() is probably the intended behaviour for
> > this. However,
> > there was no indication of this in the description.
>
> I changed the example and the text to use scm_assert_smob_type.  This
> entire section could use some modernization and less hand-waving, but
> that is a larger project.
>
> Happy hacking,
>
> Andy
> -- 
> http://wingolog.org/
>
>
> --- End Message ---