Suppose I have a subroutine which expects a hash reference, containing named parameters. The simple way to write this is: 
sub my_func
{
  my $params = shift;

  print "Message received: " . $params->{message};
  if ($params->{newline}) { print "\n" }
}

# good
my_func( { message => "Hello, world!" } );

# "Error: Not a Hash reference"
my_func( message => "Hello, world!" );

[download]
But there is a more "liberal" way to write this, which accepts the parameters in a variety of presentations (list, list-ified hash, scalar for a single "most important" param, etc): 
sub my_func
{
  my %params;
  if (ref($_[0]) eq 'HASH') {
    %params = %{+shift};
  }
  elsif (ref($_[0]) eq 'ARRAY') {
    (%params) = @{+shift};
  }
  elsif (ref($_[0]) eq 'SCALAR') {
    $params{message} = ${+shift};
  }
  elsif (scalar @_ > 1) {
    (%params) = @_;
  }
  else {
    $params{message} = shift;
  }

  print "Message received: " . $params{message};
  if ($params{newline}) { print "\n" }
}

# good
my_func( { message => "Hello, world!" } );

# also good
my_func( message => "Hello, world!" );

[download]
What are the community's thoughts on this pattern? Is this easier for users, and is the trade-off worthwhile for the maintainer?

In reply to Thoughts on "one function, flexible arguments"? by hornpipe2

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