precedence

Alan Stewart astewart at spawar.navy.mil
Sat Mar 11 17:01:20 CST 2000


~sdpm~
On 11 Mar 00, at 13:40, C. Abney wrote:

> On Sat, 11 Mar 2000, Alan Stewart wrote:
> 
> >      unless ($QUIET) {
> > 	system ( "$cmd" ) == 0
> > 		or warn "failed remote copy: $!";
> >      }
> > 
> > and Perl does what I expect :)
> 
> That sure isn't what I wanted!
> 
> I tried to write:
> 
> system ( "$cmd" ) == 0
> 	or warn ( unless ($QUIET) { warn "failed remote copy: $!";});
> 
> but perl doesn't like that. I have to do:
> 
> if ( system("$cmd") ) {
>         warn "failed remote copy: $!" unless $QUIET;
> }
> 
> 'Spose I'm just being picky, now... I was trying to maintain style
> between different code sections.  I guess I can't <g>
> 
> Why is unless so picky about where it is?
> 
Perhaps you were trying to get to something like:
    system("$cmd") == 0 or do {warn "failed remote copy: $!" unless $QUIET}
in your above example. Then the unless only modifies the statement in th do block. Not sure 
why you had warn inside of warn.

And unless does not have a precedence. Precedence is something that only applies to a string 
of operators. Unless is statement syntax, not an operator.

BTW, please reply only to the group, not To me and Cc to group. I don't need two copies.

---------------------------------------------------------------
Alan Stewart          )-[]-(           Electronics Engineer
Code D621           ~        ~         Network Operations
SPAWARSYSCEN       ~          ~  \     Satellite Communications
53560 Hull St   ( ~            ~  )    tel (619)524-3625
San Diego,CA  __|___             /|    fax (619)524-2607
92152-5001   ^\____/^^^^^^\    __| |_  astewart at spawar.navy.mil
------------^^^^^^^^^^^^^^^\__|______|_------------------------
~sdpm~

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