Qt 4.5 to be LGPL

[Bill Baxter]

On Fri, Jan 16, 2009 at 8:26 AM, BLS <windevguy at hotmail.de> wrote:
> Nick Sabalausky wrote:
>>
>> "BLS" <windevguy at hotmail.de> wrote in message
>> news:gkodf2$1aht$1 at digitalmars.com...
>>>
>>> Bill Baxter wrote:
>>>>
>>>> On Thu, Jan 15, 2009 at 4:42 AM, naryl <cy at ngs.ru> wrote:
>>>>>
>>>>> On Wed, 14 Jan 2009 18:40:19 +0300, Bill Baxter <wbaxter at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Qt 4.5 to be LGPL
>>>>>> http://tech.slashdot.org/article.pl?sid=09%2F01%2F14%2F1312210
>>>>>>
>>>>>> Now we just need a D port...
>>>>>>
>>>>>> --bb
>>>>>
>>>>> There is a binding currently in development.
>>>>> http://code.google.com/p/qtd/
>>>>
>>>> Excellent.   I didn't know anyone was working on it.  Qt is simply the
>>>> best damn GUI toolkit there is.  But I wouldn't touch it with a meter
>>>> long chopstick when it was GPL.
>>>>
>>>> I guess the D port is going to have MOC too?
>>>>
>>>> --bb
>>>
>>> I am just curious: Why QT is such a damned cool toolkit ?
>>> In other words, how is it better than wxWidgets ?
>>>
>>> I've never used QT  but QT is IMO more comparable to SWING in that it
>>> mimics  native controls/widgets...so semi-optimal.
>>> ...and what the heck is MOC ?
>>> Bjoern
>>>
>>
>> From what I gather from having recently been trying to read up on Qt:
>>
>> - The newer verions of Qt actually use the real native widgets, unlike
>> older versions of Qt.
>>
>> - MOC is a preprocessor packaged with Qt. Qt uses this concept of
>> "signals" and "sockets", which are apperently just like using a delegate
>> collection (ie, like "(void delegate())[]" or C#/WinForm's event system, or
>> something like that). Problem is, the original version of Qt is made for
>> C++, which doesn't have proper delegates (at least not last I checked). So
>> they hacked it together using a special preprocessor for C++ code.
>>
>>
>
> Phobos as well as Tango are offering support for signals and slots...does
> this mean that MOC/D is not not needed for a QtD ? Sorry for my ignorance,
> but I can't get it.
> Bjoern

They are a bit different.  In Phobos and Tango those are compile-time
signals and slots.
Meaning that all the signatures have to be known at compile time.

In Qt the binding is more dynamic.  You can call a slot in Qt even if
all you have is its name in a run-time string.
Qt also uses a similar mechanism to provide runtime dynamic
properties.  For anything derived from QObject you can ask if it has a
"color" property (again using a string), for instance.   Given enough
reflection capabilities, D could potentially turn compile time info
into similar run-time queryable strings, so I'm guessing that's why
they said they might not need MOC if D's reflection proves sufficient.
 Qt may also be able to add a

But really signals and slots is just an interesting implementation
detail about Qt.  What makes it great to me is just the completeness
of it and the amount of thought which has gone into making a clean,
clear and consistent API.   The docs are also great.

Compare these two classes:
http://doc.trolltech.com/4.3/qimage.html
http://docs.wxwidgets.org/2.8/wx_wximage.html

First off the formatting of the wx doc just makes my head hurt.  But
we'll ignore that.  Look at things like QImage::createHeuristicMask vs
wxImage::GetOrFindMaskColour().   Both functions have to do with
making a mask when you don't know what the mask color should be.  But
the Qt doc actually describes how it does what it does, the wx doc
basically just repeats the name of the function.  And the name of the
Qt function is just nicer.  And it gives you back something which you
might have a use for (a mask image) as opposed to the wx version which
just gives you the color that you have to use to go create a mask
yourself.  When are you going to need just the color?   The Qt API is
like that all over.  Almost always it has a nicely named function that
does just what you need instead of several not-so-nicely named ones
that you have to combine to get the result you want.

Also check this out:
http://doc.trolltech.com/4.3/qscrollbar

You can get to the doc for any class just with that.  Just stick the
name of the class you want doc for at the end of
doc.trolltech.com/{version}/  and it will tell you where the thing you
want is.

Wx have done a pretty good job copying the Qt doc setup, but they just
didn't quite get the details as nice.  To get the doc you have to type
exactly this:
http://docs.wxwidgets.org/2.6/wx_wxscrollbar.html
Extra 's' in the url, extra 'wx_' in the names, and '.html' cannot be omitted.

It's kinda like that all over.  Tons of small things everywhere in Qt
that just make you go, "Oh that's really nice".  You can write real
applications just fine using either wx or Qt, but very seldom do I
have those "oh wow" moments using wx.

--bb