Re: Optional parameter before reference (!proto)

sub verify {
    my $ref= \$_[-1]; pop(@_);
    my( $string )= @_;
    # ...
}
[download]

Lots of variations on that theme are possible. Avoiding subroutine prototypes is usually best with Perl.

Comment on Re: Optional parameter before reference (!proto) Download Code

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Re^2: Optional parameter before reference (!proto) by Neutron Jack (Pilgrim) on Jul 23, 2004 at 19:26 UTC
Oh, that's excellent! I'd forgotten that @_'s elements are aliases for the actual scalar parameters. We get the referencing for free, without the caller having to use a backslash. This does what I need: `sub verify { my $ref = \pop; my $string = @_ ? shift : "<default>"; $$ref = $string; # Dummy action for testing } verify $a; verify "hello", $b; print "a=$a b=$b\n"; # Expect a=<default> b=hello` [download]	[reply] [d/l]
Re^3: Optional parameter before reference (ylsned) by tye (Sage) on Jul 23, 2004 at 22:21 UTC
Interesting. I specifically didn't use `\pop` because I figured that you'd end up with a reference to a copy. But it makes sense that it is the assignment in "`my $x = pop`" that does the copying and not the pop. Thanks. - tye	[reply] [d/l] [select]