D2 GUI Libs

[Jacob Carlborg]

On 12/14/09 20:29, Jacob Carlborg wrote:
> On 12/13/09 20:44, Eldar Insafutdinov wrote:
>> Nick Sabalausky Wrote:
>>
>>> "Nick Sabalausky"<a at a.a> wrote in message
>>> news:hg394f$mr1$1 at digitalmars.com...
>>>> "Eldar Insafutdinov"<e.insafutdinov at gmail.com> wrote in message
>>>> news:hg2p87$2ttj$1 at digitalmars.com...
>>>>>
>>>>> 1) You may know the concept of signals and slots in Qt. Consider the
>>>>> following snippet:
>>>>>
>>>>> class Test : QObject
>>>>> {
>>>>> mixin Signal!("signal_1(string)");
>>>>>
>>>>> mixin Slot!("slot_1(string str)");
>>>>> void slot_1(string str)
>>>>> {
>>>>> writefln("slot_1 invoked with ~ " str);
>>>>> }
>>>>>
>>>>> mixin Q_OBJECT;
>>>>> }
>>>>>
>>>>> In Qt objects, that inherit from QObject are capable of having signals
>>>>> and slots and participate in connections. In the current scheme
>>>>> mixins of
>>>>> Signal and Slot template mix some static information into the
>>>>> class. The
>>>>> class is then scanned when Q_OBJECT template is mixed in and the
>>>>> proper
>>>>> meta-information is generated to register signals and slots in the Qt
>>>>> type system.
>>>>> As you see, this declaration is a bit ugly. In particular defining
>>>>> a slot
>>>>> requires to duplicate its signature in a mixin. What would really be
>>>>> awesome is a mechanism allowing something like:
>>>>>
>>>>> @Slot
>>>>> void slot_1(string str)
>>>>> {
>>>>> writefln("slot_1 invoked with " ~ str);
>>>>> }
>>>>> I.e we need annotations. But I am not sure how this will work. One
>>>>> of the
>>>>> possible solutions will be that @Slot expands into mixin Slot!(symbol,
>>>>> AnnotationArg1, ...).
>>>>>
>>>>
>>>
>>> Oops, slight typo:
>>>
>>>> Try string mixins, something like this:
>>>>
>>>> 1. Rename Slot to _Slot.
>>>>
>>>> 2. Do this:
>>>>
>>>
>>> // Fixed:
>>> template Slot(string decl, string body)
>>> {
>>> const string Slot = "
>>> mixin _Slot!("~decl.stringof~");
>>> void slot_1(string str)
>>> {
>>> "~body.stringof~"
>>> }
>>> ";
>>> }
>>>
>>>>
>>>> class Test : QObject
>>>> {
>>>> mixin Signal!("signal_1(string)");
>>>>
>>>> mixin( Slot!("slot_1(string str)", q{
>>>> writefln("slot_1 invoked with ~ " str);
>>>> }) );
>>>>
>>>> mixin Q_OBJECT;
>>>> }
>>>>
>>>>
>>>
>>>
>>
>> Thank you for suggestion, but while reducing redundancy it became even
>> uglier! I'll better stay with the current syntax.
>
> To make it look a little better you can do like this:
>
> template Slot (ReturnType, alias method, ARGS...)
> {
> // code
> }
>
> template Slot (alias method)
> {
> mixin Slot!(ReturnType!(method), method, ParameterTypeTuple!(method));
> }
>
> If the method is overloaded, use the first version, otherwise use the
> second. Use them like this:
>
> class Test : QObject
> {
> mixin Slot!(slot_1);
> void slot_1(string str)
> {
> writefln("slot_1 invoked with ~ " str);
> }
>
> mixin Q_OBJECT;
> }

ReturnType and ParameterTypeTuple are available in std.traits, in Tango 
they're in tango.core.Traits under slightly different names.