How to read this parameter syntax?

Development Programming & Scripting
, , ,
1

So I wanted a single reusable function to generate simple SButton widgets. I was having trouble figuring out how best to pass the function reference as an parameter. After playing around a bit I came up with this by assigning the function to an auto variable and looking at the result. It seems to work fine but I am confused about some of the syntax.

TSharedRef<SHorizontalBox> SMyWidget::ConstructButtonLayout()
{
	TSharedRef<SHorizontalBox> HorizontalBox = SNew(SHorizontalBox)
		
	+SHorizontalBox::Slot()
	[
		ConstructButton(TEXT("My Shiny Button"), &SMyWidget::OnMyShinyButtonClicked)
	];
	
	return HorizontalBox;
}

TSharedRef<SButton> SMyWidget::ConstructButton(const FString ButtonText, FReply(SMyWidget::* Callback)())
{
	return SNew(SButton)
			.Text(FText::FromString(ButtonText))
			.VAlign(VAlign_Center)
			.HAlign(HAlign_Center)
			.OnClicked(this, Callback);
}

FReply SMyWidget::OnMyShinyButtonClicked()
{
	UE_LOG(LogMyWidget, Error, TEXT("The %s button works!"), TEXT("My Shiny Button"));
	return FReply::Handled();
}

The issue I have is that I am not quite sure how I should be understanding this parameter inside the ConstructButton function FReply(SMyWidget::* Callback)(). I would’ve expected it to look more like SMyWidget::* Callback or even something more generic than that.

So I have three questions:

  1. How should I read this function parameter? FReply(SMyWidget::* Callback)()
  2. Is that the most appropriate way to pass a function as a parameter? If not, how should it be done?
  3. If this is the correct way, is it possible to make it class agnostic?
2
  1. I found that this syntax is a fairly archaic (though functional) version of std::function. I suspect there is an Unreal way of handling this though.