CreateSP() and Lambda functions for Slate UI in UE5

Development Programming & Scripting
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1

I was going over this article and trying it out for myself, but I get an error in my code in the 2 lines where I use the CreateSP() function to pass the value from my window to my checkbox widget(If I understood this correctly).

The first CreateSP() for FOnCheckStateChanged did not have the same parameter as shown in the document page.
The second CreateSp() for FIsChecked couldn’t be called because FIsChecked was not a namespace or a class.

I assume something has changed in Slate while updating to UE5 since the document looks like it was created when UE4 was in use.

I did some searching and thought I could use lambda functions to pass a reference of the value to replace the CreateSP() function, but I am not sure how to use lambda functions in general, so I may be wrong.

TLDR;
Is it still possible to use CreateSP() for Slate in UE5 and if not, can lambda functions replace it?

2

Hmm looking at the source code of auto-generated attributes, you don’t need to pass in a delegate, you simply need to use the right setter and pass in the function directly.

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image1270×837 124 KB

For SP, the setter is an overload of the attribute name, so this should work :

SNew(SCheckBox)
.OnCheckStateChanged(this, SQuickStartWindowMenu::OnTestCheckboxStateChanged)
.IsChecked(this, &SQuickStartWindowMenu::IsTestBoxChecked)

For lambdas, use the _Lambda setter :

SNew(SCheckBox)
.OnCheckStateChanged_Lambda([](ECheckBoxState NewState) {
    //...
})
.IsChecked_Lambda([]() -> ECheckBoxState {
    return ECheckBoxState::Unchecked;
})
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