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

Hi Monks. I am trying to call a function by passing a scalar variable and a array reference as a argument. The function call is as below. 

&executeCommand($command, \@paramlist);

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Here the parameter $command is again a name of a function module which needs to be triggered with the \@paramlist as the argument list for the function pointed by $command. In the function definition of executeCommand i should call the function pointed by the $command with the \@paramlist as the arguments for that function. How do i do that , i am able loop through the parameter list and get the values but how can i trigger the function.Kindly suggest how to proceed. Definition of executeCommand is as below

sub executeCommand{
    
    print "Inside ExecuteCommand\n";
    print "Currently executing Command name:".$_[0];
    print "\n";
    my $array_reference = $_[1];
        foreach my $element (@$array_reference){
       print "Parameter:".$element."\n";
     }
}

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Replies are listed 'Best First'.
Re: Passing arguments to functions.
by BrowserUk (Patriarch) on Apr 25, 2012 at 11:26 UTC 

    #! perl -slw
use strict;

{
    package Other;

    sub commandFunc {
        print "Doing Other::commandFunc with args: [ @{ $_[0] } ]";
        return;
    }
}

sub executeCommand{
    no strict 'refs';
    my( $func, $argRef ) = @_;
    *{$func}->( $argRef );
}


my @a = 1.. 10;
executeCommand( 'Other::commandFunc', \@a );

__END__
C:\test>junk
Doing Other::commandFunc with args: [ 1 2 3 4 5 6 7 8 9 10 ]

    [download]
    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    The start of some sanity?
[reply]
[d/l]
      The use of symbolic reference is an elegent solution for a 'use once' script. The effort to write a hash of hard references (Called 'dispatch table' in a previous post) will probably be repaid in the maintainence of 'industrial strength' software. Unfortunately, most perl applications lie somewhere inbetween, where the choice is one of preference.
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        The effort to write a hash of hard references (Called 'dispatch table' in a previous post) will probably be repaid in the maintainence of 'industrial strength' software.

        Sorry, but you do not know what you are talking about.

        The code I posted uses a hash-based dispatch table. It is called the symbol table.

        There is simply no advantage to adding another layer of indirection here; and no additional risk or maintenance effort in avoiding that extra layer.

        Which makes all your talk of "use once" and "industrial strength", nothing more than cargo-culted, pseudo-CompSci balderdash!

        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

        The start of some sanity?
[reply]

        You don't need symbolic references at all 

        #!/usr/bin/perl --
use strict; use warnings;
use CGI;
sub dier { die " dier die @_ " }
warn main->can('CGI::new')->();
main->can('dier')->( 'now' );
__END__
CGI=HASH(0x99a1fc) at - line 5.
 dier die now  at - line 4.

        [download]
[reply]
[d/l]
Re: Passing arguments to functions.
by Anonymous Monk on Apr 25, 2012 at 11:05 UTC
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Re: Passing arguments to functions.
by Anonymous Monk on Apr 25, 2012 at 11:17 UTC
    What is a "function module"? An example of what $command actually contains would help.

    I recommend passing a code reference as first argument, this is the most generic way to solve this kind of problem. 

    use 5.010;
use strictures;

sub execute_command {
    my ($code, $params) = @_;
    say 'Inside executeCommand';
    say 'Currently executing: ', ref $code;
    foreach my $element (@{ $params }) {
        say "Parameter: $element";
        $code->($element);
    }
}

my $command = sub {
    # I am going to print the arguments I receive!
    say @_;
};

execute_command($command, \@paramlist);

    [download]
[reply]
[d/l]
      Hi, Thanks for your reply, i will try your approach and let you know the results. $command is a normal perl function , it might do anything as you defined it can just print the passed arguments as well. In my case $command is a value got by parsing an xml which is a name of a function.. $command = launchapp; launchapp is the function name which needs to be triggered.
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