perlquestion
muba
Hi,<BR><BR>
I am writing a simple plugin system. I'm not sure whether I'm going to use it, but it's more like a way to explore Perl.<BR><BR>
So, I have an array which contains packages names. Those packages should have a sub 'ReceiveMessage'.<BR>A package called Communications contains a sub 'SendMessage'.<BR>This SendMessage loops over the array to check which packages do have a ReceiveMessage and send a message to it. Currently, the array consists of one item: "Communications".<BR><BR>
<CODE>
package Communications;
sub SendMessage {
my $msg = join("", @_);
foreach my $cpack (@main::plugpack) {
if (defined eval "${cpack}::ReceiveMessage") {
eval "\&${cpack}::ReceiveMessage('$msg')";
}
}
}
sub ReceiveMessage {
print "Communications::ReceiveMessage('$_[0]')\n";
}
</CODE>
Of course I call the SendMessage sub once: <CODE>&Communications::SendMessage("Hello, World!");</CODE><BR>
The strange thing is, I get output like I called SendMessage twice:
<code>
Use of uninitialized value in concatenation (.) or string at D:\device\modem\internet\Xitami\cgi-bin\index.pl line 48.
Communications::ReceiveMessage('')
Communications::ReceiveMessage('Hello, World!')
</code>
It appears to me that ReceiveMessage is not only called when the message is sent, but also when SendMessage checks it's existance. How can I prevent this?<BR><BR>
<B>Update:</B> just clarified the last paragraph a little<BR>
<B>Update:</B> removed line of code which was coded in a inconsistent style and only was there for debug purposes :)