From 2243178be4300769c7b604e1317276a0b80a4b36 Mon Sep 17 00:00:00 2001
From: Neil H watson <neil@watson-wilson.ca>
Date: Sun, 3 Dec 2017 11:06:03 -0500
Subject: [PATCH] Intial attempt at a Perl entry on subroutines

---
 sheets/_perl/subroutines | 67 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 sheets/_perl/subroutines

diff --git a/sheets/_perl/subroutines b/sheets/_perl/subroutines
new file mode 100644
index 0000000..814a8a1
--- /dev/null
+++ b/sheets/_perl/subroutines
@@ -0,0 +1,67 @@
+# The reserved word 'sub' defines a subroutine.
+
+# Basic subroutine with on parameter:
+
+sub mysub {
+   my $param = shift;
+
+   # Do stuff here
+
+   return $myvalue
+}
+
+$x = mysub( "value" )
+
+# Named parameters to subroutines:
+
+sub named_params_example {
+   my ( $arg ) = @_;
+   # Use my ( $self, $arg ) = @_; if you are in object land.
+
+   say $arg->{one};
+   say $arg->{two};
+}
+
+# Calling the above subrouting:
+
+named_params_example({
+   one => "First argument",
+   two => "Second argument"
+});
+
+# Named parameters with default values:
+
+sub named_params_with_defaults {
+   my ( $arg ) = @_;
+   # Use my ( $self, $arg ) = @_; if you are in object land.
+   
+   # Set defaults
+   #         If option given      Use options   Else
+   my $one = exists $arg->{one} ? $arg->{one} : "default1";
+   my $two = exists $arg->{two} ? $arg->{two} : "default2";
+}
+
+named_params_with_defaults({ one => "override arg 'one'" });
+
+# Return named params from a subroutine:
+
+sub foo {
+   my $clause = 'This is a clause';
+   my @param = qw/ one two thee /;
+
+   return ({
+      clause => $clause,
+      params => \@param
+   });
+}
+
+my $r = foo();
+
+say "clause = [$r->{clause}]";
+for my $p ( @{ $r->{params} } ) {
+   say "param = [$p]";
+}
+
+# More help with Perl's fabulous perldoc command:
+
+perldoc sub