Sure- declare your subs at the beginning of your script. For example, 

#!/usr/bin/perl
use strict;
sub foo($);   #declare foo as a sub that accepts 
              #a single scalar, to be defined later

foo;          #compile time error
foo 1;        #okay - no error

sub foo($) {  #actual foo implementation
  print shift;
}

[download]

Update: tachyon rightly points out that this won't always behave as expected - and gives two good links for reference. Perl tries to figure out the context of your arguments, which may (or may not) DWIM. 

sub foo($$);      #two scalar arguments
foo $bar;         #error
foo @bar;         #error
foo $bar, $baz;   #ok
foo $bar, @baz;   #no error, but does it do what you want?

[download]

In reply to Re: Enforcing formal arguments at compile time? by jsprat
in thread Enforcing formal arguments at compile time? by dargosch

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.