A "wholesome" QProperty

ronM71

It's a common practice, define private data member, define public (or protected) data accessor (set/get methods).

I've been looking at QProperty to help me reduce lines of code, but found out it requires me to write the set/get methods. Is there a more "wholesome" Qt Macro that would also provide the content of the simple "get/set" methods?

I know, I can easily write one myself, just wanted to know if Qt already has it.

giesbert

No, there is not.
The point is, the get/set methods are needed by moc for creation of the meta object code.
And moc does not do pre compiling.

You have to write the getter and setter.

andre

I think "this discussion":http://developer.qt.nokia.com/forums/viewthread/4382/ may interest you.

florent.revelut

an easy way is define your own macro if you always have the same thing to do :
@

#define commonMember(type,x)
protected:
type m_ ## x
public:
type get ## x () { return m_ ## x;}
void set ## x (type a){ m_## x = a;}
@

From my point of view however, it tends to ugliness : I prefer to write my trivial getters on demand, if required (less code, less bug, less test)

_Macro not compiled, not tested, so not working, it's just to give the spirit of it ;-) _

giesbert

THis macro has one problem: It does not work with Q_PROPERTY, and that's what he asked for.
For Q_PROPERTY it's currently not possible.

ZapB

But you could use this macro in conjunction with Q_PROPERTY couldn't you? Or does moc try to be smart and actually complain if it can't find the getter/setter? I've not tried it.

giesbert

We tried one combined macro, not two...
It's wrth a try

giesbert

Ok,

I tried it out. This works (is compilable):

@
#define commonMember(type,x)
protected:
type m_ ## x;
public:
type get ## x () { return m_ ## x;}
void set ## x (type a){ m_ ## x = a;}

class MainWindow : public QMainWindow
{
Q_OBJECT
Q_PROPERTY(bool test READ gettest WRITE settest)

commonMember(bool, test)

public:

@

JulienMaille

Is it still impossible to generate Q_PROPERTY from a macro?

raven-worx

"Qt 5.1 introduces":http://qt-project.org/wiki/New-Features-in-Qt-5.1 a new keyword for Q_PROPERTY:
@New keyword in Q_PROPERTY: MEMBER let you bind a property to a class member without requiring to have a getter or a setter.@