At 16:51 2015-07-07, Ken Dibble <[email protected]> wrote:
Gene stated:
VFP does not do lazy evaluation much at all! (The only
exception to this that comes to mind is the second and third
parameters to iif().)
Well, I was thinking of these types of cases:
PROCEDURE MyProc
LOCAL var
var = 4
IF var = 4 OR anothervar = .T. && anothervar is undefined
RETURN "OK"
ENDIF
ENDPROC
This will compile fine, and it will run without error as long as var
= 4. VFP does not evaluate what comes after the OR in these cases. It is my
Yes, short-circuit evaluation with logical operators is common
in languages.
understanding that some languages do evaluate all elements of the
statement before attempting to resolve it, and will fail at runtime
even if the code compiles.
Yes.
On procedure calls, all of the parameters are going to be
evaluated before executing the call except for rare cases. iif() is
such a case. We can not create such procedures ourselves in VFP.
Sincerely,
Gene Wirchenko
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