CODEWITHSUNDEEP
delphiif-statement
Pieter B
Pieter B

Reputation: 1967

Use big if clauses or stack them?

what's a better way to do things?

if f1() and f2() then...

or

if f1() then
  if f2() then

or:

fBoolean1 := f1()
fBoolean2 := f2()

if fboolean1 and fboolean2 then...

In the first example I'm not sure which of the two functions gets evaluated. In the second example f2 only gets evaluated if f1 evaluates true and in the third example both f1 and f2 get evaluated.

What's the best way to do this?

Upvotes: 3

Views: 200

Answers (1)

Andreas Rejbrand
Andreas Rejbrand

Reputation: 108963

The compiler is smart. In your first sample, if f1 returns false, then f2 will not even be called (unless you change the default compiler settings by disabling lazy evaluation or boolean short-circuit evaluation). Hence, the first option is equivalent to the second one (again, unless you have changed the default settings).

Consequently, perfomance-wise, the two first options are better. Otherwise, it is a matter of taste. The second option will yield two blocks of code, with two levels of code indentation (if you follow the standard rules of indentation, as you seem to do). Perhaps you'd prefer the first option for this reason.

Of course, if you need to use the value returned by f1 and f2 later, perhaps several times, the third option is superior.

Upvotes: 8

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