On 9/11/09 6:27 PM, "Michael Käppler" <xmichae...@web.de> wrote:
>
>
>> You need to amend the definition of the method in lily-guile.hh, since
>> it's also used directly in the C++ code, with no optional arguments:
>>
>> 53 SCM ly_assoc_get (SCM key, SCM alist, SCM def);
Can't you just use
SCM ly_assoc_get (SCM key, SCM alist, SCM def,
SCM strict_check = SCM_BOOL_F);
in lily-guile.hh?
And with this definition, all the 3-parameter calls to ly_assoc_get will
assume that strict_check is false?
>>
> Hmm... I don't exactly understand the LY_DEFINE macro. Is it possible to
> implement this
> with overloading or have all C++ calls of ly_assoc_get to be changed to
> use all four parameters?
>> + programming_error ("Cannot find key ~S in alist, setting to ~S.",
>> ly_scm2string (key), ly_scm2string (default_value));
>>
>> I think what Carl is getting at here is that you can't pass these
>> string values using format with programming_error () without adding
>> the macro `(_f', but this shouldn't be used in this case since it
>> internationalizes the message.
Actually, that wasn't what I was getting at, but you got the right answer
from Neil, anyway.
>>
> programming_error (to_string ("Cannot find key %s in achain, setting to
> %s.",
> ly_scm2string (key), ly_scm2string
> (default_value)));
>
> Is this basically the right way to do this?
>
>> There's a bigger problem here though, since it's not clear what the
>> value of the key is going to be before converting it: ly_scm2string
>> will only work if the scheme value is a string. This naturally
>> applies to default_value too, which could conceivably be any scheme
>> object.
>>
> What about adding a type check to ly_scm2string and add the possibility
> to convert from symbols and numbers too?
> Isn't there a guile built-in method for converting any scheme object in
> a readable string?
Yes, there is. It's object->string. See
http://www.gnu.org/software/guile/manual/html_node/General-Conversion.html#G
eneral-Conversion
HTH,
Carl
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