Re: [Boost-build] Usage of complex expressions in regular if-statements apart from string literals.

Subject: Re: [Boost-build] Usage of complex expressions in regular if-statements apart from string literals.
From: Jurko Gospodnetić (jurko.gospodnetic_at_[hidden])
Date: 2012-07-19 06:29:18

   Hi.

> I am kindly asking you if it is possible to extend without much pain bjam
> functionality in order to support complex expressions (like per-lists
> comparisons or rule invocations) in regular if-statements?
> For example, it is not possible for now to perform neither such comparison:
> if "bla" "bla" = "bla" "bla"
> {
>      ECHO Yes! ;
> }
> else
> {
>      ECHO No... ;
> }

   Actually, all variables are lists so you can do this by using two 
additional variables as in:

> local lhs = foo bar ;
> local rhs = foo bar ;
>
> if $(lhs) = $(rhs)
> {
>     ECHO Yes! ;
> }
> else
> {
>     ECHO No... ;
> }

   or you can do something like this to check a rule's return value:

> rule foo
> {
>     return figaro bar ;
> }
>
> local expected-result = figaro bar ;
> if [ foo ] = $(expected-result)
> {
>     ECHO Yes! ;
> }
> else
> {
>     ECHO No... ;
> }

   Hope this helps.

   Best regards,
     Jurko Gospodnetić