Spec - I want to replace the first presenter in a SpPanedLayout

Question

Is that possible without needed to rebuild the whole presenter?

I am trying this code, but it does not work correctly:

self layout remove: (self layout children first).
self layout add: aNewPresenter.

It actually removes the presenter, but the new presenter is not placed at the first place but at the end.

Answer 1

In Spec2, all layouts are dynamic (meaning they can be modified at runtime), but each layout has different API and hence they need to be modified in different ways. In particular, SpPanedLayout has just two children: first and second (they can be displayed vertically -top to bottom- or horizontally -left to right-).
This means that unlike SpBoxLayout , in SpPanedLayout the use of #add: and #remove: messages are not necesary and will not always produce the desired result, and since #add: will try to add the presenter at the end of the list, in case it succeeds it will always be the second.
Instead, you can just set the children, and you will be effectively replace the presenter at the place you want.

Assuming you have the gtk backend installed, this code:

presenter := SpPresenter new.
presenter application: (SpApplication new useBackend: #Gtk).

presenter layout: (SpPanedLayout newHorizontal
    first: (presenter newLabel label: 'I will replace this');
    second: (presenter newLabel label: 'Powered by Pharo');
    yourself).
    
presenter openWithSpec title: 'Example replace paned presenter'.

presenter layout 
    first: (presenter newImage image: (presenter application iconNamed: #pharoBig)).

Will replace the label "I will replace this" with the pharo logo in runtime.

And it will produce this output: