Re: [wxGlade] Extra code / Extra properties

[Brendan S. (eTRIX) <bre...@et...>]

On 7/11/17 6:07 am, Dietmar Schwertberger wrote:
> Hi!
>
> Is anyone actually using "Extra properties for this widget"?
>
> I was just about to prepare a code example for how to use the
> CustomWidget for adding classes that are not supported natively by
> wxGlade.
>
> My example would be a matplotlib canvas. This requires some imports
> and a bit of code before and after creation, as it requires an object
> to be created and supplied as argument. The workaround would be to
> derive a class and use this instead of the original matplotlib canvas.
> That's possible, but not too nice.
>
> I'm completely missing a way to specify the code to be executed before
> creation of an object.
>
> Also, for the code after creation, there's only the method to specify
> extra properties.
> E.g. property "maxLength" and value "10".
> This is then magically converted to
> self.my_custom_widget.SetMaxLength(10).
>
> Personally, I would prefer to have three fields:
>  * Extra import code (added on module level, just as now).
>  * Extra setup code (to be called right before the widget is
> instantiated)
>  * Extra code (to be called right after the widget is instantiated)
>
> With this setup, I'm wondering whether the Extra properties make sense
> any more.
>
> What do you think? Do you have real-world examples? Do you have any
> preferences in favour or against such a change?
>
> In theory the Extra properties have the advantage that they are
> language-neutral, but I have some doubts whether this has practical
> relevance.

I've used `CustomWidget` to implement a plot canvas from `wx.lib`

I put the following in the Extra Code section for the widget instance.

    import my_custom_plot


and specify the following as the Class (in Common tab).

    my_custom_plot.MyCustomPlot


The custom widget class definition and constructor are:

    import wx
    from wx.lib import plot as wxplot

    class MyCustomPlot(wxplot.PlotCanvas):

        def __init__(self, *args, **kwds):

            #! these attributes are used in other methods when updating
    the graph,
            #! and can be specified by Extra Properties in wxglade,
            #! however I now use a `set_props()` method from the main app
            #! to set these properties (and others that may not be
    settable in the constructor)
            self.line_colour = kwds.pop('line_colour', "red")
            self.line_width  = kwds.pop('line_width',  1) 
            self.axes_colour = kwds.pop('axes_colour', "blue")

            wxplot.PlotCanvas.__init__(self, *args, **kwds)

            self.clear()