Please suggest how to improve my code. My function lchompx basically removes several occurences of a certain string from the beginning of another string. For example, $r=lchompx('abababcdef','ab') sets $r to 'bcdef'. The details, however, are tricky:

• If lchompx is invoked with only one argument, this argument is the string to be removed, and the function operates on $_, i.e. $_='abc';$r=lchompx('a') sets $r to 'bc'.
• If it is invoked without arguments, leading multiple occurences of newline, "\n" are removed from a copy of $_.
• In void context, the argument of lchompx is changed in place, i.e. ...; lchompx($x,'abc'); modifies $x and ...; lchompx('abc'); lchompx both modify $_

.

Here is my implementation:

sub lchompx {
  my $lchompstr=quotemeta(@_ > 0 ? $_[-1] : "\n");
  my $change_in_place=!defined wantarray;
  my $default_argument=(@_<2);
  unless($change_in_place) {
    @_ = $default_argument ? $_ : @_;
  }
  if($change_in_place && $default_argument) {
    s/^($lchompstr)*//
  } else {
    $_[0] =~ s/^($lchompstr)*//
  }
  $_[0]
}
[download]

This seems to work, butit is ugly, since the substitution expression has to be repeated for the special case "Changing $_ in place". Any idea how to code this in a nicer way?

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