Am Montag, 26. November 2007 23:45 mkajdas.mkprod wrote:
> I must be doing things differently than everyone else but every class that
> I create that contains a window does not release that window's memory. My
> fluid code looks something like this:
>
> class FL_EXPORT TDset_Dialog {} {
> Function {TDset_Dialog()} {} {
> Fl_Window TDsetWindow {
> private xywh {390 417 500 190} type Double box ...
> } {
> ..
> }
> Function {~TDset_Dialog()} {} {
> code {;} {}
> }
> }
>
> When this class is created and deleted it has a leak. If I add:
>
> TDsetWindow->clear(); delete TDsetWindow;
The clear() is not necessary, it is called by the TDsetWindow Dtor.
> to ~TDset_Dialog(), the leak is fixed.
> I assumed that when the class is deleted, it would cleanup the window and
> everything else, but it is not. I want to find out if I am doing something
> wrong or my assumption is incorrect or I have to use Fl_Group first or ?
The question is concerned rather with a general C++ feature.
The above class TDset_Dialog is not itself a Widget or Window (derived from
Fl_Widget or Fl_Window) but a window wrapper class maintaining a dynamic
window object. Dynamic resources (objects created on heap via 'new' or
malloc()) must be deleted explicitely as in the following scetch
class A {
Fl_Window* window; // window pointer as member
public:
A() {window = new Fl_Window(...);}
~A() {delete window;} // explicit deletion
};
(A==TDset_Dialog). To distinguish from it is the case where a class ´B´ has
a Window *object* as member:
class B {
Fl_Window window; // window object as member
public:
B() : window(...) {}
~B() {} // nothing to do
};
Here the Dtor of the window object is automatically called when the B Dtor
is called. But the code generated by FLUID is of the first kind (otherwise
"->" and "delete" could not be applied to ´TDSetWindow´).
Yet a note on automatic widget deletion in FLTK:
The only widgets, FLTK deletes automatically are the children of a Group
(in the case the Group is deleted). Widgets without a parent, i.e. widgets
which are not child of a Group, will be not deleted automatically by
deletion of any other Group, they must be deleted explicitly. Top level
windows are such widgets without a parent, i.e. top level windows must be
deleted always explicitly -- so far at least a deletion is wanted.
Window wrapper classes as your TDset_Dialog should be used only for top
level windows, I think, otherwise the window could be deleted twice: by
its parent group and by the Dtor of the wrapper class.
Hartmut
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