variable in perl

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

Hi Friends,

In the code that my senior has written there is a function which has the first few lines as given below

sub WriteLog($$)
{
my ( $logtype, $logtext ) = @_;
my ( $out,@items)=();
push @tems, ( ref($logtext) eq 'ARRAY' ) ? @$logtext : $logtext;
}

And the call to the WriteLog is like :

WriteLog( "INFO","*******Import Begin *****");

=======================================
[download]

Two arguments are sent to the WriteLog but in the definition there is a $$ ..I couldnt understand why $$ is used here.
And what are ref , @$ used for ?
Can any one help me ?

Thanks in advance
Veera

formatting fixed by holli

Comment on variable in perl Download Code

Replies are listed 'Best First'.
Re: variable in perl by tlm (Prior) on Jun 17, 2005 at 12:55 UTC
The `$$` is a prototype; it specifies that the function `WriteLog` takes two scalars as arguments (see prototypes in perlsub). In the expression `@$logtext`, `$logtext` is actually a reference to an array, and `@$logtext` dereferences this reference to access this array. `ref` is an operator that, when given a reference as argument, returns the type of reference it is (ref). To better understand `ref` and `@$logtext` see perlreftut. the lowliest monk	[reply]
Re^2: variable in perl by sveera (Initiate) on Jun 17, 2005 at 18:01 UTC
Hi tlm , thanks for your reply.this helps me a lot... bye Veera	[reply]
Re: variable in perl by dorward (Curate) on Jun 17, 2005 at 12:59 UTC
$$ is a prototype, described in perldoc perlsub. ref is described in perldoc -f ref, and is used here to find out if $logtext is a scalar or a reference to an array. @$ dereferences the array reference (thus treating it as a regular array).	[reply]
Re^2: variable in perl by sveera (Initiate) on Jun 17, 2005 at 18:02 UTC
Hi dorward, thanks a lot for your response.i shall go through the help available in the perl man pages. Thanks Veera	[reply]