Improving version(...)

[Vladimir Panteleev]

On Mon, 18 Oct 2010 19:15:47 +0300, F. Almeida  
<francisco.m.almeida at gmail.com> wrote:

> The version() { ... } blocks would greatly improve from support of
> boolean operators, which would make code much more readable.
>
> Let us assume, for example, that I have several version identifiers
> (VERSION1, VERSION2, VERSION3, VERSION4, etc.) and that a block of
> code may be compiled in the cases of VERSION1 or VERSION3. It would
> prove the simplest if one could simply use boolean operators to
> express combinations of valid versions and thus be able to do
>
>
> version(VERSION1 || VERSION3)
> {
>  // ...
> }

I remember reading somewhere that this limitation is deliberate.

I believe the reason for this is that programmers with a C background will  
tend to abuse this feature to create near-unreadable code (#ifdef mess).

The solution (workaround) for this, is to create new versions for specific  
features you wish to enable/disable. For example:

version(Demo) {} else version(Lite) {} else { version = EnableFeatureX; }
version(EnableFeatureX) { ... }

One thing people seem to agree with is that version statements could use  
the negation (!) operator. Then the above could be written as:

version(!Demo) version(!Lite) { version = EnableFeatureX; }

-- 
Best regards,
  Vladimir                            mailto:vladimir at thecybershadow.net