Expansion Problem?

OK. I sort of see what's happening there, but the original
example is much 
more surprising (and incorrect, to my eyes). When you do:

> DEFAULT = e f ;
> VAR = ;
> echo xxx-$(VAR:E=$(DEFAULT)) ;

You're getting two elements in the output list because VAR
is empty, so it 
resolves to the contents of DEFAULT, which contains two
items. Those get 
multiplied by the prefix, producing the expected output.

In the original case:

> DEFAULT = e f ;
> VAR = a b c ;
> echo $(VAR:E=$(DEFAULT)) ;

>  >jam
> a b c a b c

I don't see what's happening here. Because DEFAULT
contains two items, the 
:E modifier doubles the length of the list?! Why? The
semantics of 
$(VAR:E=$(DEFAULT)) should be: "If VAR is not empty,
give me the contents of 
VAR. If VAR is empty, give me the contents of
DEFAULT". Instead, it seems to 
be ... no nevermind, I can't come up with an explanation
that makes any 
sense. ( "If VAR is empty, give me DEFAULT. If VAR is
not empty, then for 
each element of DEFAULT, give me another copy of VAR?"
)

Am I missing something here?

-Brian

----- Original Message ----- 
From: "Christopher Seiwald" <seiwaldperforce.com>
To: <cjamallsopgmail.com>; <jammingperforce.com>
Sent: Wednesday, September 06, 2006 12:45 PM
Subject: Re: [jamming] Expansion Problem?


>| Using jam 2.5 - is this normal?
> |
> | DEFAULT = e f ;
> | VAR = a b c ;
> | echo $(VAR:E=$(DEFAULT)) ;
> |
> |  >jam
> | a b c a b c
> | ...found 7 target(s)...
> |
> | The E modifier should only use it's value if the
variable is unset?
>
> It's consistent with the rest of the productizing
variable expansion.
>
> Just as if you said:
>
> DEFAULT = e f ;
> VAR = ;
> echo xxx-$(VAR:E=$(DEFAULT)) ;
>
> You'd get
>
> % jam
> xxx-e xxx-f
>
> That's not to say it is useful or not surprising, but
it is the way the
> rest of it works.
>
> Christopher
> _______________________________________________
> jamming mailing list  -  jammingperforce.com
> http://maillist.perforce.com/mailman/listinfo/jamming
>
> 
_______________________________________________
jamming mailing list  -  jammingperforce.com
http://maillist.perforce.com/mailman/listinfo/jamming