Ruby for Perl Programmers

G. Wade Johnson

My Ruby Experience

Dabbled with Ruby a couple of times.

Hired to be a Ruby programmer almost 2.5 years ago.

Differences in Two Acts

• Language/Syntax Differences
• Culture/Mindset Differences

Everything is an Object

• Even integers:
  • 1.upto 5
  • 4.odd?
• Even strings:
  • "WADE".downcase
  • "hello".include? "lo"
• Even nil
  • nil.nil?
  • nil.to_i

Simple/Obvious Differences

• Methods can end in ?, !, or =
• Either false or nil is falsey.
• Variables outside a function are not visible inside.
• Any capitalized identifier is a constant.
• Atoms start with : and are collapsed into one instance.

Structure

Use begin/end or do/end instead of {/}.

Most of the time.

Classes

• Defined with a class/end block
• Constructor is named initialize
• Instance variables are spelled @variable
• Define getter/setter methods with attr_accessor, attr_reader, attr_writer
• Methods are defined using def
• Classes are open, or subject to modification

Modules

• Group of methods or namespace for modules and classes
• Including a module adds its methods to the class as instance methods
• Extending a module adds its methods to the class as class methods

Class Example

Open example.rb

Blocks are Major Feature

• Lots of methods use blocks
• Like a closure
• Specify arguments as part of declaration
• Similar to map or sort in Perl
• Used to wrap functionality to be applied by the function
• Sometimes just for the sake of using a block
  • Initialization
  • tap

Containers

Rich set of methods for dealing with each kind of container.

arrays

+, -, [], []=, any?, bsearch, collect, collect!, count, each, first, grep, grep_v, include?, last, map, etc.

hashes

[], []=, any?, default, dig, each_key, each_pair, each_value, empty?, has_key?, has_value?, etc.

enumerables

all?, any?, chunk, count, each_entry, each_with_index, find, include?, member?, etc.

Example Code

Open blocks.rb

Metaprogramming

• Used a lot by libraries/frameworks
• Used to create DSLs
• Used to do some impressive magic (think Devel::Declare)
• Beginning to see some push-back

Gems

• Their modules are called gems.
• Major tools are gem and bundle
• bundle supports installing multiple versions of a gem on the same system

Building Projects

• rake instead of make
• Rakefiles contain Ruby code (sometimes in the rake DSL)

Culture/Mindset

Optimize for programmer happiness. is one of their mottos.

I don't find myself particularly happier working in Ruby.

• Some playful methods/names.
• Less ceremony than some languages.
• Power tools

Ruby on Rails

Most seem to program in Ruby on Rails not in Ruby.

They also don't seem to recognize that fact.

Rails (libraries) extend Ruby in a lot of ways; often by monkey-patching standard classes.

Speed

They realize that Ruby is not the fastest runtime around and are mostly okay with it.

Neophiles

Many in the Ruby community seem attracted to new stuff.

• New JavaScript libraries.
• New JavaScript transpiler languages.
• Elixir

Reminds Me of Perl From a Few Years Ago

• Ruby programmers sometimes act like they have invented tested code.
• Some gems are almost completely undocumented.
• Ruby programmers talk quite a bit about meta-programming and open classes.
• Lots of excitement for clever solutions.

Two main figures in the community.

• Matz (Yukihiro Matsumoto) - Ruby
• DHH (David Heinemeier Hansson) - Rails

Comparison to Perl

In many ways, they look down on Perl, while realizing that Ruby was influenced by Perl.

Mostly not as hostile as the Java community.

Some Really Bright People

• Doing language/design/community work with Ruby.
• Pushing good design principles that are new-ish.
• Some (re)discovery of ideas that are already in other languages.
• Some discovery of ideas that have been around for years.

Best Practices?

• Small methods
• Small classes
• Seem to avoid local variables

Convention over Configuration

• Strong Rails influence
• Works pretty well, except when it doesn't
• They are willing to override the preference when necessary
• Can be a problem when the convention changes.

Questions?