RE: [PHP-DEV] Possible problem in the parser

At 13:01 14.03.2003, Ford, Mike               [LSS] wrote:
> > >Just to make this completely clear, in left-associative PHP
> > >
> > >    b = a==1? 4:a==2? 5:6;
> > >
> > >is equivalent to
> > >
> > >    b = (a==1? 4:a==2)? 5:6;
> >
> >
> > NO it is not equal. Either '==' has higher precedence OR '?:' has.
> > See one of my previous mails where i showed where the error is.
>
>Yes, it is -- believe me, I've researched this extensively.  It is NOT 
>about precedence, but associativity.  If you want me to be totally 
>completist about this:
>
>Starting from:
>
>    b = a==1? 4:a==2? 5:6;
>
>precedence rules make this equivalent to:
>
>    b = (a==1)? 4:(a==2)? 5:6;
>
>but this is still ambiguous -- which ?: phrase do you evaluate 
>first?  Associativity provides the answer: in PHP, where ?: is left 
>associative (i.e. the left most ?: is evaluated first), the result is 
>equivalent to:
>
>    b = ((a==1)? 4:(a==2))? 5:6;
>
>On the other hand, in c, where ?: is right associative, the equivalent is:
>
>    b = (a==1)? 4:((a==2)? 5:6);
>
>which, apart from the additional (unnecessary) parentheses around the == 
>comparisons, is exactly what I said before.
>
>QED


Ok Mike, i did not took left association into accound becuase it is stupid.
Since the whole thing is messy at the moment and there is no reason to
keep BC for messy things which shouldn't be done anyway i suppose we
make ir right associative.

Andi?


marcus