From kde-bindings  Mon Feb 11 13:59:24 2013
From: Arno Rehn <arno () arnorehn ! de>
Date: Mon, 11 Feb 2013 13:59:24 +0000
To: kde-bindings
Subject: Re: [Kde-bindings] question about the hello.cpp example
Message-Id: <5118F93C.2000500 () arnorehn ! de>
X-MARC-Message: https://marc.info/?l=kde-bindings&m=136059118317206

On 11/02/13 04:16, John J Foerch wrote:
> Hello,
Hello,

> I have been studying the example program hello.cpp from
> http://techbase.kde.org/Development/Languages/Smoke#hello.cpp as I
> develop a set of Qt/Smoke bindings for my favorite Scheme dialect, and
> there is one thing about the program that has me mightily confused.
>
> qtcoreBinding and qtguiBinding seem to be used almost interchangeably.
> The QApplication constructor is looked up in qtcore, but at the end of
> the program, the destructor is looked up in qtgui.  The "set smoke
> binding" call for both qapp and widget use qtgui, and nothing uses
> qtcore.  In my experiments in my scheme implementation of this program,
> I have found that I can completely remove all references to qtcore in
> the program and use qtgui instead, and it still works, but not the other
> way around.
Yes, you can replace qtcore with qtgui in this case, because only QtGui
classes are used (i.e. QApplication and QWidget). Method lookups work 
across module boundaries, but they can be faster if you do the call in 
the correct module.
The QtCore smoke module will implicitly be loaded by the QtGui smoke 
module (you might leak memory then, however, if you don't delete the 
qtcore Smoke instance at the end).

The SmokeBinding instance that you set for each object should be the 
correct one for the respective module, i.e. you have to have one 
SmokeBinding instance per Smoke module (that you use).

> What is the relationship between these two modules?  Does qtgui contain
> qtcore?  Are they both needed in this program, or in any program that
> uses qtgui?  Can anybody clarify?
No, qtgui doesn't contain qtcore. It only implictly loads it. Some types 
in qtgui depend on classes from qtcore (the respective classes are then 
flagged as "external" in qtgui and you'll have to look them up in the 
other modules), so in a more complex app you'll need it anyway.

-- 
Arno Rehn
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