Re: [sigc] Re: [Boost-users] Signals & Slots

From: Doug Gregor (dgregor_at_[hidden])
Date: 2005-01-07 09:13:22

On Jan 7, 2005, at 9:06 AM, Carl Nygard wrote:
> On Fri, 2005-01-07 at 08:19 -0500, Douglas Gregor wrote:
>> On Jan 7, 2005, at 6:12 AM, Murray Cumming wrote:
>>> 3. In "Slot Binders"
>>> Can you expand on this question: "TODO: answer questions: a) What's 
>>> up
>>> with the No Clue entry, anyone?", please. In fact, please just ask 
>>> your
>>> TODO questions on this mailing list.
>>
>> So the intent of retype() and retype_return() is to allow casting of
>> the argument and return types of a function. Are these also required
>> when performing implicit conversions? For instance, will the following
>> work?
>>
>>    long Func3(double val, string str);
>>
>>    sigc::signal<int, float, string> sig;
>>    sig.connect(sigc::ptr_fun(&Func3));
>>
>> If I'm right in assuming that the code will not compile (because the
>> signatures do not match exactly), then the "No Clue" could be replaced
>> by "Not Applicable", because
>> Signals performs all of the implicit conversions.
>
> In that case, it's supported in Boost.Bind, so retype/retype_return() 
> is
> included with sigc::bind/compose/hide/group.  Correct?

Implicit conversions are handled in both Boost.Bind and in 
Boost.Signals. I don't know enough about sigc::bind/compose/hide/group 
to answer the rest.

>>    - About ptr_fun/mem_fun: you can use them in either library, if 
>> you'd
>> like to be more explicit.
>
> I couldn't find docs on boost.org for ptr_fun, just mem_fun.  What am I
> missing?

Well, there's std::ptr_fun, and you could always wrap it in bind() if 
you wanted. ptr_fun really is just syntactic (de-?)sugar.

>>    - About bind: bind is now in the C++ Library TR (an addendum to the
>> standard, which should be approved in the near future), so we're 
>> forced
>> to build on it to create any signals & slots library for the standards
>> committee. (We'll have a long, uphill battle if we try to introduce 
>> our
>> own special binders and don't support bind).
>
> Do you have a link to the TR?

There is a draft here:

   http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1711.pdf

If you're familiar with Boost.Function/Boost.Bind, you'll be familiar 
with the TR versions. Very little has changed.

        Doug