Conserving memory - was SPUG: Fw: greetings

[ced at carios2.ca.boeing.com]

>...
> Hmmm... so just out of perverse curiosity, what would be the most 
>efficient way of generating the old behaviour in a newer version of 
>Perl?

> while( ($var = <FILE>) ? 1 : undef )	# ?????

> Actually, this isn't just perverse curiosity: I'd like to know under 
>*exactly* what set of conditions while(*) actually means while( 
> defined(*) ) .  Is it only in the very specific cases of

>while(<FOO>)
>while( $var = <FOO> )

I suspect yes but even after carefully reading perlop, I'm not sure. 

>?  Is it anytime the <> operator appears in the expression?  E.g. 
> what would be the semantics of:

> while( ($var = <FOO>) , $var )

With an added chomp, your line above does appear to recapture the 
older semantics. The following prints:

abc
def
0
abc
def

#!/usr/bin/perl -w
use strict;
my $start = tell DATA;
print while <DATA>;
seek(DATA, $start, 0) or die;
my $var;
while( chomp($var = <DATA>), $var )   {
   print $var, "\n";
}
__END__
abc
def
0


rgds,
--
Charles DeRykus

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