Can you give a motivating example from WebKit?
Geoff
On Apr 19, 2014, at 1:09 PM, Filip Pizlo <fpi...@apple.com> wrote:
> Hey everyone,
>
> When guarding code with macros that are always defined, such as
> ASSERT_DISABLED (it's always either 0 or 1), we have a choice between:
>
> if (!ASSERT_DISABLED) {
> // do things
> }
>
> and:
>
> #if !ASSERT_DISABLED
> // do things
> #endif
>
> I'd like to propose that anytime the normal if would be semantically
> equivalent to the preprocessor #if, the normal if should be used.
>
> We don't lose any compiler optimization, since even at -O0, the compiler will
> constant fold the normal if. We do gain a lot of clarity, since the control
> flow of normal if statements is subject to proper indentation.
>
> The "semantically equivalent" requirement still allows for #if to be used for
> thinngs like:
>
> - Guarding the placement of fields in a class.
> - Guarding the definitions of other macros (in the case of ASSERT_DISABLED,
> we define ASSERT in different ways guarded by #if's)
> - Guarding the definition/declaration/inclusion of entire functions, classes,
> and other top-level constructs.
>
> Thoughts?
>
> -Phil
>
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