On Thu, Dec 16, 2010 at 07:12, Peter Schneider <[email protected]>wrote:
>
> I strongly feel that the current order of constructor calls for mixins is
> wrong.
> I didn't want to necropost a thread by Ralf Nieuwenhuijsen[1] that is about
> 2.5
> years old...but it basically explains the reason of this wrong behavior an
> I
> therefore took the liberty and "stole" his description from that thread ;)
>
I don't recall this prior conversation, but I think I disagree with one of
Ralf's givens:
> > Why? Because the mixin can make no assumptions about the class it's mixed
> > in.. so it won't be calling or setting properties other than its own.
> >
> > But the class using the mixin knows its using the mixin. It wants to use
> the
> > mixin in the contructor, but it can't.
>
That is true only if the mixin is included with the "include:" member of the
class description. A mixin can also be included into a class with
qx.Class.include(), in which case the class does not know that the mixin is
available. The current order of constructor calls is appropriate for this
usage. I can see a valid argument for changing the constructor order when
the mixin is included directly into a class, and leaving it as it is when
qx.Class.include() is used... but then there's an inconsistency which may
disallow the mixin from being used both ways. A mixin must be able to be
used both ways.
>
> Example:
> ========
> It is not possible to do this:
>
> <code>
> qx.Class.define("app.ContextTable",
> {
> extend : qx.ui.table.Table,
> include : qx.ui.table.MTableContextMenu,
>
> construct : function (tableModel)
> {
> this.base(arguments, tableModel);
> // This *fails*, 'cause the mixins constructor was not yet called!
> this.setContextMenuHandler(0, this.__handler, this);
> },
>
Hmmm... You can either put this.setContextMenuHandler() into the defer
section (probably your best option), or try this:
qx.Class.define("app.ContextTable",
{
extend : qx.ui.table.Table,
include : qx.ui.table.MTableContextMenu,
construct : function (tableModel)
{
this.base(arguments, tableModel);
// Set a timer to add our context menu handler after MTableContextMenu
has been mixed in
qx.util.TimerManager.getInstance().start(
function(userData, timerId)
{
this.setContextMenuHandler(0, this.__handler, this);
},
0, this, null, 1);
},
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