Fw: [jamming] Another compatibility problem in Jam2.4

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-02-20 23:33:36

Some important info for the merge...

----- Original Message -----
From: "Craig McPheeters" <cmcpheeters_at_[hidden]>
To: <jamming_at_[hidden]>
Cc: <rmg_at_[hidden]>
Sent: Wednesday, February 20, 2002 10:46 PM
Subject: [jamming] Another compatibility problem in Jam2.4

>
> Hi,
>
> In early Feb, Miklos (boga_at_[hidden]) reported that the syntax for 'in'
> changed in the current development version of Jam 2.4. His reported
> fix is to alter the jamgram.yy file:
>
> > < | arg `in` list
> > to
> > > | expr `in` expr
>
>
> A second problem is with expressions like the following:
>
> list = 1 2 3 4 ;
> element = 1 ;
>
> if ! $(element) in $(list)
> {
> Echo Wrong. ;
> }
>
> With Jam 2.3 the echo is not reached. With 2.4-dev, the echo is executed.
> If you add brackets to the example, jam 2.4 will do the right thing. The
> change breaks a lot of my code.
>
>
> One solution is to revert that section of jamgram.yy back to an earlier
> style, with the extensions that 2.4 needs. The new section which is
working
> for me is:
>
> expr : arg
> { $$.parse = peval( EXPR_EXISTS, $1.parse, pnull() ); }
> | arg `=` arg
> { $$.parse = peval( EXPR_EQUALS, $1.parse, $3.parse ); }
> | arg `!=` arg
> { $$.parse = peval( EXPR_NOTEQ, $1.parse, $3.parse ); }
> | arg `<` arg
> { $$.parse = peval( EXPR_LESS, $1.parse, $3.parse ); }
> | arg `<=` arg
> { $$.parse = peval( EXPR_LESSEQ, $1.parse, $3.parse ); }
> | arg `>` arg
> { $$.parse = peval( EXPR_MORE, $1.parse, $3.parse ); }
> | arg `>=` arg
> { $$.parse = peval( EXPR_MOREEQ, $1.parse, $3.parse ); }
> | expr `&` expr
> { $$.parse = peval( EXPR_AND, $1.parse, $3.parse ); }
> | expr `&&` expr
> { $$.parse = peval( EXPR_AND, $1.parse, $3.parse ); }
> | expr `|` expr
> { $$.parse = peval( EXPR_OR, $1.parse, $3.parse ); }
> | expr `||` expr
> { $$.parse = peval( EXPR_OR, $1.parse, $3.parse ); }
> | arg `in` list
> { $$.parse = peval( EXPR_IN, $1.parse, $3.parse ); }
> | `!` expr
> { $$.parse = peval( EXPR_NOT, $2.parse, pnull() ); }
> | `(` expr `)`
> { $$.parse = $2.parse; }
> ;
>
>
>
> Cheers,
> Craig.
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