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View Full Version : Signal-Slot, object instances



ct
16th February 2006, 18:25
I am using a designer..and I was curious whether one could make a signal slot connection without making a instance of a object but declaring a object..

MyObj *obj;
connect(obj,SIGNAL(),this,SLOT());

obj=new MyObj();


just curious whether this would be valid

zlatko
16th February 2006, 18:46
What actually do you mean?
In designer genearated files i never see something like that :rolleyes:

ct
16th February 2006, 18:57
Well in designer you don't actually have the
MyObj *obj;

it is written at the public member Object explorer.
Now, generally before using the object we need to create a instance for it..I am asking can we use the object without creating its instance in a signal slot connection ..and what may its consequences be.

orb9
16th February 2006, 20:08
MyObj *obj;
connect(obj,SIGNAL(),this,SLOT());

This will crash.

You are passing an uninitialized pointer to connect(). If you're lucky obj is initialized with 0 and connect() checks for 0-pointers, but generally accessing an uninitialized object is simply shooting yourself in the foot.