[ruby/optparse] More on tutorial (#16)

-   Added example in "Argument Converters"; it doesn't seem right for a tutorial to have no example in one of its topics (and instead just linking elsewhere).
-   Added section "Command-Line Abbreviations."
 -  Added section "Keyword Argument into," showing how to:
     -  Collect options.
     -  Check for missing options.
     -  Provide option defaults.

https://github.com/ruby/optparse/commit/39d39676c4

1 files changed, 12 insertions, 0 deletions

diff --git a/doc/ruby/missing_options.rb b/doc/ruby/missing_options.rb
new file mode 100644
index 0000000000..9428463cfd
--- /dev/null
+++ b/doc/ruby/missing_options.rb
@@ -0,0 +1,12 @@
+require 'optparse'
+parser = OptionParser.new
+parser.on('-x', '--xxx', 'Short and long, no argument')
+parser.on('-yYYY', '--yyy', 'Short and long, required argument')
+parser.on('-z [ZZZ]', '--zzz', 'Short and long, optional argument')
+options = {}
+parser.parse!(into: options)
+required_options = [:xxx, :zzz]
+missing_options = required_options - options.keys
+unless missing_options.empty?
+  fail "Missing required options: #{missing_options}"
+end