[Qt-interest] How To: pass extra data to object slots from menu action signals?

[kent williams]

I found a way around this problem, but somehow it feels sneaky:

1. Derive a new class from QAction, and add the data I need to this class.
2. Add my derived-from-QAction class to the QMenu after setting the member data.
3. In the action connected to my action, cast sender() to my derived
type, and retrieve the needed data from it.

As elegant as the signal/slot paradigm is, I'd think there would be a
more 'Qt' way of doing this.

On Mon, Feb 1, 2010 at 3:35 PM, kent williams <nkwmailinglists at gmail.com> wrote:
> I am working on a program that dynamically adds and removes actions
> from menus, based on adding and deleting objects in the user
> interface.
>
> This causes a problem in QT -- actions attached to a QMenu send a
> triggered() signal, but that signal can only be connected to a slot in
> my class with a similar signature, e.g. triggered() or triggered(bool
> b).
>
> I figured out that I could use a QSignalMapper to map triggered() from
> a menu action to a slot that takes a single string argument.  But what
> I'd like to do is pass in two strings. In other words I have a
> multilevel menu like this
>
> File
>    Save
>       Type1
>           Object1
>           Object2
>       Type2
>           Object1-1
>           Object1-2
>
> And I want to trigger this slot
>
> void SaveSomething(Type, ObjectName);
>
> What I'm asking is this: is there a way to have a Signal send more
> information to an object?
>
> The only thing I could figure out is to construct strings containing
> both arguments, and then use QSignalMapper to map that Action to that
> string.
>
> Is there a better way?
>