why does location of function matter?

[smartyollie]

I have run into a situation several times at my current job where the location of a perl function affects whether it works or not. I've never had this happen before and feel like I'm missing something obvious. The current scenario happens on both Windows (Strawberry Perl) and UNIX (Solaris v5.8.4). I have a function called PostValidate with one argument. When I put the function definition AFTER the main body of code, it runs; when I put the function before, it fails with

Too many arguments for main::PostValidate at y.pl line 349, near "$ofile)"

The call within the main body looks like this:

if ($validate) {
PostValidate($ofile);
}

I don't have any prototypes defined and I'm really at a loss as to why it should matter where the function is. Any ideas?

[BrowserUk]

I don't have any prototypes defined and I'm really at a loss as to why it should matter where the function is. Any ideas?

You don't show us the critical piece of information, namely the function definition; but from the error message, I'd guess that your function looks something like this:

sub PostValidate() {
#...............^^
   # stuff here. ...
}

Which defines a function that takes no arguments.

If that is seen before the function is called; it will complain that you passed too many arguments.

If it is not seen until after the function call is compiled, then the prototype is too late to be applied.

Does that fit your code?

[Anonymous Monk]

With warnings enabled that would cause a "X called too early to check prototype" warning.

[smartyollie]

##########################
sub PostValidate() {
##########################
my ($file) = @_;
my $cmd = "wc -l $file";
{more stuff}

[davido]

That should be written as:

sub PostValidate {
    ...
}

As you have it declared, sub PostValidate does declare a prototype. An empty prototype means no args may be passed (assuming Perl sees the subroutine is declared before its first use, as you've discovered).

[Anonymous Monk]

I don't have any prototypes defined

sub PostValidate() {

An empty prototype () is still a prototype.

You should always Use strict and warnings.

[AnomalousMonk]

And the obligatory links: Prototypes and especially Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen.

[GotToBTru]

"I don't have any prototypes defined" and yet the error says Perl thinks you do. In the eternal battle between what the programmer meant and what the compiler interprets, there can be only one winner ;)

[GotToBTru]

The explanation would be easier if we saw your code.

[Anonymous Monk]

Can't reproduce. Could you provide a small piece of working example code that demonstrates the problem?