On Monday, 24 December 2018 at 11:18:44 UTC, Ron Tarrant wrote:
I found a mention that in the definition of a delegate, a
function parameter and its type could be replaced by an
underscore:
myTestRig.addOnDestroy(delegate void(Widget w) { quitApp(); } );
became:
myTestRig.addOnDestroy(delegate void(_) { quitApp(); } );
I was trying to find some further documentation on this, but
I'm coming up empty.
Questions:
1) What is this called (substituting an underscore in this
manner)?
2) Where can a learn more about it?
1)
The underscore does nothing and it's just an identifier.
Really it just means "unused". It's frequently used in loops to.
Ex.
foreach (_; 0 .. 100)
{
// Do something 100 times ...
}
2)
There is really nothing to learn about it since it's not really
thing.
However that's not to say there isn't underscore magic in D.
Ex. double underscore identifiers are currently reserved (For
fields) and shouldn't be used because their behaviors aren't
defined in the same way as regular fields.
That's however a very different thing and unrelated to this
"underscore magic".
