Re: Is gcc able to handle anonymous functions?

[address@hidden]

On 4 juil. 2012, at 20:10, Marc Hohl wrote:

> Am 04.07.2012 13:29, schrieb David Kastrup:
>> Marc Hohl <address@hidden> writes:
>> 
>>> Hello list,
>>> 
>>> the topic is somewhat over my head, but perhaps someone with more
>>> insight can answer this question?
>> I think that gcc likely can, don't know about g++, and we don't want to
>> rely on it anyhow.
> Ok.
> 
> Well then, is there an alternative?
> 
> I want to get rid of bar-line.cc (issue 1320), and I have managed to get all
> definitions but Bar_line::non_empty_barline into scheme.
> 
> In lily/note-spacing.cc, I have
> 
> Grob *bar = Pointer_group_interface::find_grob (right_col,
>                                                     ly_symbol2scm 
> ("elements"),
> Bar_line::non_empty_barline);
> 
> The simple approach
> 
> bool non_empty_barline =
> ly_scm2bool (scm_call_1 (ly_lily_module_constant 
> ("bar-line::non-empty-barline"), right_col->self_scm ()));
> 
> with
> 
> (define-public (bar-line::non-empty-barline grob)
> (and (grob::has-interface grob 'bar-line)
>     (pair? (ly:grob-extent grob grob X))))
> 
> doesn't work.
> 
> I see that in lily/pointer-group-interface.cc the function above is defined as
> 
> Grob *
> Pointer_group_interface::find_grob (Grob *me, SCM sym, bool (*pred) (Grob *))
> {
> [snip]
> }
> 
> What is bool (*pred) (Grob *)?
> 
> Is there a way to get a scheme function in this place, or do I have to put
> the remaining definition of bar-line.cc into another file?
> 
> Regards,
> 
> Marc
> 
> 
> 
> 
>> 
> 
> 
> 
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I just realized that there's an easier way to do this w/ existing code 
conventions.  You can overload Pointer_group_interface::find_grob so that it 
accepts a simple closure as the third argument.  Then, wrap the Scheme function 
in a simple closure.

Cheers,
MS