$incl has to contain a reference to a function (e.g. $incl = \&my_func), or the name of a function if strict 'subs' is off (e.g. $incl = 'my_func'). In your case, it contains much more than that. It contains a bit of (uncompiled) Perl code.

You have two options.

• You can use eval EXPR to execute the Perl code. That's rather slow, and it can be vulnerable to injection attacks.

  push(@incl,"&CreateLogInForm(\$page,\$error)");
  
  foreach $incl (@incl) {
    $page .= eval $incl;
  }
  [download]

• You can wrap the function call (your Perl code) with an argument-less subroutine. This method doesn't suffer from the problem listed above.

  push(@incl, sub { &CreateLogInForm($page,$error) });
  
  foreach $incl (@incl) {
    $page .= &$incl;
  }
  [download]

There are subtle differences in the meaning of $page and $error between the two:

• {
    my $page  = 'abc';
    my $error = 'def';
  
    push(@incl,"&CreateLogInForm(\$page,\$error)");
  
    $page  = 'ghi';
    $error = 'jkl';
  }
  
  foreach $incl (@incl) {
    my $page  = 'mno';
    my $error = 'pqr';
    $page .= eval $incl;   # Uses 'mno' and 'pqr'
  }
  [download]

• {
    my $page  = 'abc';
    my $error = 'def';
  
    push(@incl, sub { &CreateLogInForm($page,$error) });
  
    $page  = 'ghi';
    $error = 'jkl';
  }
  
  foreach $incl (@incl) {
    my $page  = 'mno';
    my $error = 'pqr';
    $page .= &$incl;   # Uses 'ghi' and 'jkl'
  }
  [download]