About delegates

[philippe]

Hi there
I understand the concept about delegates;
The documentation shows examples all clear but I don’t know how to link - for example a class containing functions to drive textfield view - it in the GUI manager?

[cvp]

@philippe Not sure that I correctly understand your request (usual for me 😉), but try this code, it could perhaps help you to understand how to use delegate.

import ui

class MyTextFieldDelegate (object):
    def textfield_should_begin_editing(self, textfield):
        return True
    def textfield_did_begin_editing(self, textfield):
        pass
    def textfield_did_end_editing(self, textfield):
        pass
    def textfield_should_return(self, textfield):
        textfield.end_editing()
        return True
    def textfield_should_change(self, textfield, range, replacement):
        v.name = f'textfield_should_change: {range} , {replacement}'
        return True
    def textfield_did_change(self, textfield):
        pass

v = ui.View()
v.frame = (0,0,600,400)
v.background_color = 'white'

tf = ui.TextField()
tf.frame = (100,100,200,32)
tf.delegate = MyTextFieldDelegate()
v.add_subview(tf)

v.present('sheet')

[philippe]

@cvp
Thank u @cvp
So , I suppose I must have to link this class somewhere in the GUI when creating the view, right?

[ccc]

tf is a ui.TextField so the "hooking up" is done on the line tf.delegate = ...

[philippe]

@ccc
It’s all right
You must implement the hook in the code
No way to do it during the creation of the view in the GUI manager
Thanks

[cvp]

@philippe said

No way to do it during the creation of the view in the GUI manager

Sorry for that, I had not read enough your request. Now, I understand... Sincerely, I don't know.
Anyway, you would have to write some code for the delegate actions but perhaps you could in the GUI manager tell you will use it.

In the Custom Attributes of your TextField, in GUI Manager, use

{'delegate':MyTextFieldDelegate}

And your .py could be, without self

import ui

class MyTextFieldDelegate (object):
    def textfield_should_begin_editing(textfield):
        return True
    def textfield_did_begin_editing(textfield):
        pass
    def textfield_did_end_editing(textfield):
        pass
    def textfield_should_return(textfield):
        textfield.end_editing()
        return True
    def textfield_should_change(textfield, range, replacement):
        v.name = f'textfield_should_change: {range} , {replacement}'
        return True
    def textfield_did_change(textfield):
        pass


v = ui.load_view()
v.present('sheet')

[philippe]

@cvp
Well done 👍🏻
I was thinking it will be nice to get this in the documentation …..

[cvp]

@philippe Don't forget that doc has already been a big work for the developer. And if you search via Google for Pythonista, UI, Custom Attributes, you will find some examples.