johnnywang has asked for the wisdom of the Perl Monks concerning the following question:

Hi, two similar questions. I found out that one can do the following to pass parameters to references of functions: 
my $ref = \&test;
$ref->(1);

sub test{
   print "param: ", shift,"\n";
}

[download]
But how to pass the parameter without introducing the variable $ref (i.e., something like \&test->(1))? And how to pass parameters to anonymous subs? Thanks.

Replies are listed 'Best First'.
Re: How to pass parameters to anonymous subs and sub references?
by jdporter (Paladin) on Nov 08, 2004 at 19:41 UTC
    For q1, all you need is parens: 
    (\&test)->(1);

    [download]
    As for q2: Do you have an anonymous sub? What's it look like? In the typical situation, you have a ref to the sub, e.g. 
    my $ref = sub { print "(@_)\n" };

    [download]
    in which case you do as you already showed: 
    $ref->(1);

    [download]
    If not that, then what?
[reply]
[d/l]
[select]
Re: How to pass parameters to anonymous subs and sub references?
by BrowserUk (Patriarch) on Nov 08, 2004 at 19:47 UTC 
    sub { print "@_"; }->( qw[ hello world ] );
hello world

    [download]
    Examine what is said, not who speaks.
    "Efficiency is intelligent laziness." -David Dunham
    "Think for yourself!" - Abigail
    "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon
[reply]
[d/l]
Re: How to pass parameters to anonymous subs and sub references?
by pg (Canon) on Nov 08, 2004 at 19:50 UTC

    Something similar to what jdporter sort of mentioned when he was answering your question 2... A typical way to assign callback functions when you use Tk (or whatever ...) is:

    my $b = $mw->Button(-command => sub {foo("abc", "123")});

    [download]

    Not much as passing parameters to anonymous sub, but rather you were forced to create anonymous sub.

[reply]
[d/l]
Re: How to pass parameters to anonymous subs and sub references?
by Arunbear (Prior) on Nov 08, 2004 at 19:52 UTC
    Also 
    &{\&test}(1);

&{sub { print "param: $_[0]\n" }}(1);

    [download]
[reply]
[d/l]
Re: How to pass parameters to anonymous subs and sub references?
by NetWallah (Canon) on Nov 08, 2004 at 22:10 UTC
    Simpler .. 
    my $x=sub{print shift}; 
&$x('this that');

    [download]

        Earth first! (We'll rob the other planets later)

[reply]
[d/l]

Back to Seekers of Perl Wisdom