If conditions continue to be evaluated even after the "if" has been satisfied

NOYB · March 18, 2023, 6:56am

Function XYZ()
  print "Why evaluating XYZ?  The If condition was already satisfied."
  XYZ = false
End Function

Sub XXX
  If true Or XYZ() Then
    print "True"
  End If
End Sub

Doing something like this and don’t want/need to evaluate subsequent conditions once the “If” is satisfied.

If ( _
( (X = "A") ) Or _
( (X = "B") And  Not (Yn = Ys) ) Or _
( (X = "C") And  Not (Mn = Ms) ) Or _
( (X = "D") And  Not (Qn = Qr) ) Or _
) Then
  do this ...
End If

If X is “A” do this…
If X is “B” And Yn does not equal Ys do this…
If X is “C” And Mn does not equal Ms do this…
If X is “D” And Qn does not equal Qr do this…

Why even when X is satisfied by “A” the subsequent conditions continue to be evaluated?

Is this an intended behavior with some purpose?

mikekaganski · March 18, 2023, 9:51pm

Basic has no boolean short circuiting. See tdf#153142. IMO, it is unfortunate; but implementing it now would be an incompatible change, because current code could rely on the unconditional side effects of all the expressions.

NOYB · March 19, 2023, 2:10am

Maybe an option flag with default to current behavior.

mikekaganski · March 19, 2023, 6:44am

I don’t see a compelling reason. It would introduce incompatibility with other versions and apps (AOO) - and it would not make anything possible that wasn’t possible earlier. This is just a syntax sugar, allowing to express the same functionality in a different form, having its own price. It would be nice if it existed from the beginning, but it doesn’t worth it at this time.

NOYB · March 19, 2023, 7:51am

Order of “If” conditions in high iteration loops can be a huge difference.
Avoid high cost evaluations by preceding with a simple test to exclude.

mikekaganski · March 19, 2023, 8:21am

What do you mean? Are you explaining what could be simplified by the short-circuiting? Isn’t it clear that it’s obvious? But my point was, that it is already possible, just using a bit more elaborate syntax? So the proposal, while could provide a bit shorter expressions, does not introduce anything that wasn’t yet possible in the language using a different syntax.