[lokisetup] New feature : boolean variables and expressions

[Ludwig Nussel]

On Thursday 30 March 2006 02:20, Stéphane Peter wrote:
> [...]
> About Boolean Expressions :
> 
> Many elements support the 'if' or 'condition' attribute to reference  
> complex expressions
> using the Setup boolean variables. The expressions have to follow the  
> following syntax:
> 
> expression := [!]<operator>(<expression1>,<expression2>) |
>                [!]<boolean name>
> 
> Supported operators are : + (logical "and"), | (logical "or"), and ^  
> (logical "exclusive or").
> Any expression can be negated by a ! prefix.
> An undefined boolean is the same as a false boolean.
> 
> Some examples :
> 
> Match Fedora on PowerPC system:
>     +(fedora,ppc)
> Match one of SuSE, Redhat 9 or Fedora, on all but Intel:
>    +(^(suse,+(redhat,distro-major-9),fedora),!x86)

Intereting idea but the syntax is really weird. If you move the
operator inside the parenthesis you could say it's like lisp.

(and (or? suse (and redhat distro-major-9) fedora) (not x86))

You could also just use xml to represent that expression. You don't
need an additional parser then.

cu
Ludwig

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