See def -- Deal nicely with undefined values that I posted in 2000. But I'd actually do it differently: 

sub def {
    my $var= \$_[0];
    my $val;
    while(  @_  &&  ! defined $val  ) {
        $val= shift @_;
    }
    $$var= $val
        if  ! defined wantarray;
    return $val;
}

# For example:
my $size= def( $ENV{MAXSIZE}, -s $swapFile, -1 );

# Or void context causes $size to be modified
def( my $size, $ENV{MAXSIZE}, -1 );

[download]

- tye        

In reply to Re: RFC: Defined-Or for before Perl 5.10 (def(...)) by tye
in thread RFC: Defined-Or for before Perl 5.10 by molecules

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