How to use screen language's 'If'? [answered&solved]

[fluxus]

Okay so... for various reasons, where various means I-want-a-screen-that-calls-a-screen-to-update-my-data,
I'd like to run an action (specifically, a function) depending on whether or not I provide the object to update.

Happily, I found the If function.

So I'm trying this:

Code: Select all

If(False, true=update.selfadjust, false=None)

...and if complains that object of type None has no function called 'selfadjust'. And rightly so, because the parameter 'update' was None in this case, since that is the default value.

But.

If ought to evaluate to false.
So..
There's no lazy evaluation here, 'If' evaluates both statements regardless of the test condition?

[fluxus]

And.. well, under the assumption that I'm right, I wrote a work-around class which solves my problem and makes things work, but, well.. it also kind of renders the If redundant, so I'm still interested in answers / better solutions.

Code: Select all

    class NoUpdate:
        def __init__(self):
            pass
        
        def selfadjust(self):
            pass

[PyTom]

What exactly are you trying to do? It seems like you could just use general python code.

Code: Select all

screen blah(update):

    python:
        if update is not None:
            action = update.selfadjust
        else:
            action = None

    textbutton "Self-Adjust" action action

[fluxus]

Eh..?
You can use python code directly while inside a screen?
Damn.

Could you pen that down for inclusion in the documentation effort for 6.18?
I have been jumping a significant amount of hoops back and forth between SL, script and classes in order to get things functioning - looks like life just got a lot easier.

Anyway, this was the entire code for the screen in question:

Code: Select all

screen verify_move(container, from_inventory, to_inventory, text, update=NoUpdate()):
    zorder 2
    frame:
        xsize .5
        ysize .3
        xalign .5
        yalign .8
        vbox:
            text text.format(container.name) style "selection_caption" xalign 0.5
            button:
                style "selection_choice_button"
                text "Ja" style "selection_choice"
                action [    renpy.curry(to_inventory.add)(container), 
                            renpy.curry(from_inventory.remove)(container), 
                            If(update, true=update.selfadjust, false=None),
                            Return("Done") ]
            button:
                style "selection_choice_button"
                text "Nej" style "selection_choice"
                action Return("Done")

...Aaaand in case anyone is wondering, what this does is to move one item from one inventory to another inventory. If the player chooses Yes/Ja, that is.

[PyTom]

It's in the documentation.

The one restriction is the Python code can't have side effects, since it's run as part of the screen prediction process.

[fluxus]

You're right, it is, apologies. While I've read a good portion of it in order to know the various possibilities at the beginning, later on I've generally read the documentation on a need-to-know basis. I think this was the biggest surprise thus far, though.

About the side effects, I could still sort a list into smaller lists by item type through in-screen python; that alone means I can slaughter a class I specifically wrote for overcoming that problem.
Though arguably the whole data structure ought to be changed from using a list to using a dict.
No time, though :]

Thanks for letting me know - my next project is going to be so much easier what with all I've learned while doing this one :>