Jay McGavren's Journal

Notes from Jim Weirich - Building Blocks of Modularity...

Update 2009-05-05: Saw this talk again today at RailsConf and had a chance to fill in some missing pieces…

Is there a grand unified theory of software development?
Principles:
	SOLID
	Law of Demeter
		Method chains not good - only talk to objects in local environment.
	DRY
	Small Methods
	Design by Contract
Myer on Coupling: old, imperfect model that doesn't extend well to dynamic languages.  From best to worst:
	No coupling
	Data coupling
		Data local to two modules: simple data
	Stamp coupling
		Data local to two modules: structured data
	Control coupling
		Method usually has a "flag" parameter that controls which algorithm it uses
			ex: Array.instance_methods(true) #What does true mean?!
			ActiveRecord#find (:first, :all, etc.)
	External coupling
		Global data: simple data
	Common coupling
		Global data: structured data
	Content coupling
Connascence
	Things that are born together, and change together.  A change in one requires a corresponding change in the other.
	Originally applied to software by Meilir Page-Jones in early 90's.
Connascence of Name:
	class Customer
		def email; blah; end
	end
	def send_mail(customer)
		customer.email #Change Customer#email's name, you must update this call.
	end
Rule of Locality:
	Connascence of name between method parameter and a reference in the same method doesn't matter at all.
	Connascence of name between two separate libraries matters a lot.  It's why APIs must be frozen.
Connascence of Position:
	:orders => {"3" => "1", "5" => "2"}
	[ [ Order.find(3), true], [ Order.find(5), false ] ]
	Order of parameters decides behavior.
	Really bad:
		def process(order, expedite, confirmation_number, ...); blah; end
		[order, true, 2374]
		Easy to forget order of parameters, especially if you're passing 3, '
	Better:
		class OrderDisposition
			attr_reader :order
			attr_reader :expedite
			attr_reader :confirmation_number
		end
	Methods that take hash parameters are better than positional arguments, because each argument is labelled and can be re-ordered or omitted.
Degree matters:
	Some types of connascence are worse than others.
	Connascence of Name better than Connascence of Position.
Rule of Degree:
	Convert higher degrees of connascence into weaker forms.
		Example: refactor from positional method params to an options hash with named keys (CoP -> CoN).
Connascence of Meaning
	Consider "magic numbers" (these are bad):
		<input type="checkbox" value="2">
		if params[:med][id] == "2" #Have to do case-like statement in totally different module.
			@medication.given = false
		end
Contranascence
	Things conflicting with each other.  (Always in name?)
		#my_xml_lib
		module Kernel; def node; end; end
		#my_graph_lib
		module Kernel; def node; end; end #Conflict!
	Example is classes that must be namespaced to avoid conflict (XML::Node, YAML::Node)
Connascence of Algorithm:
	Logic repeated in multiple places - not DRY.
	Bad:
		def add_check_digit(digits); digits + ((10 - digits.foobar{|d| d + 5} % 10).to_s; end
		def check?(digits) check_sum(digits.foobar{|d| d + 5}) == 10; end
		Change digits.foobar{|d| d + 5} in one place, you must change it in both places.  Better not forget!
	Better:
		def add_check_digit(digits); digits + ((10 - foobar(digits) % 10).to_s; end
		def check?(digits) foobar(digits) == 10; end
		def foobar(digits); blah; end #Shared routine
		Change the shared routine, and you change the logic everywhere you need to.
Connascence of Timing
	Race conditions.
	Bad if called from multiple threads:
		def increment
			@amount += 1
		end
	Use Java-like synchronized declarations on methods to ensure they are thread-safe.
Connascence of Type
	See What Every Programmer Should Know About Object Oriented Design, Meilir Page-Jones
Connascence of Execution
	See What Every Programmer Should Know About Object Oriented Design, Meilir Page-Jones
Connascence of Value
	See What Every Programmer Should Know About Object Oriented Design, Meilir Page-Jones
Connascence of Identity
	See What Every Programmer Should Know About Object Oriented Design, Meilir Page-Jones

Notes from Jay Philips on Adhearsion...

One of the more exciting talks at MountainWest RubyConf… Looks like I could have something simple running in a weekend.

Asterisk front end. Native integration with Rails. Project:

	dialplan.rb:
		adhearsion {
			simon_game
		}
		sandbox {
			play "hello-world" #Sound file stored on server.
			menu "hello-world" do |link|
				link.adhearsion 1 #Dialpad number to press.
				link.foobar 2
			end
		}
	events.rb
	components/
		sandbox/
			sandbox.rb
			sandbox.yml
				username: dfsklh
				password: dafsjkh
		my_component/
	config/
	startup.rb

Notes from Adam Dunford & Jason Edwards: Improving the Usability of Your Ruby on Rails Applications

Usability: Can a user accomplish THEIR goal?
Use actual users in usability testing.
Investment in usability usually offers 10x-100x return in increased profit.
Creating structure:
	Organize
	Prioritize
		Most important stuff is most obvious
	Group
		Similar stuff goes together
	Separate
	Differentiate
Don't defy user expectations (ex: link description doesn't match where it goes) - it makes them mad.
Reduce barriers:
	Allow quick account creation and signon.
		Pict.com lets you upload pictures even before you create an account.
	Don't require framework (Flash, Javascript, Silverlight) to be enabled/installed, at least not right away.
	Try to anticipate problems.
		Phone number validation - for God's sake, don't use 3 separate fields!
Affordances:
	Increase text size.
	Make form fields bigger.
	Add label tags that move cursor to field when clicked.
Give feedback:
	Make it clear and obvious that your app is responding appropriately.
	If validation fails, mark the fields with problems directly (indicator *right* next to them).
	Anticipate actions:
		Really cool - validate fields (in Javascript?) even before user submits form.
Simplify:
	"Every time you provide an option, you're asking the user to make a decision."  Avoid it where possible.
	Principles:
		Reduce
			How many elements can you take out of the signup form?
				Get rid of COPPA age validation.
				Tumblr got it down to 2 - username and password.
		Replace
		Hide
			Hide things that can't be acted on right now.
		Remove
			Remove info that isn't necessary.
Use terminology user is comfortable with: it's "delete", not "destroy".

Integrum invades MountainWest RubyConf...

Hey to @jamesbritt from the #mwrc Zonie row! Would've said hi first thing this morning, but you were enjoying your talk with that bum. :) 8 minutes ago from web

#mwrc attendees interested in Puppet might want to take a look at Rush (RUby SHell) as well: http://rush.heroku.com/ 11 minutes ago from web

Back at #mwrc after looong walk to RV. Shoulda left laptop where it was, but glad to be fully wired again. 12 minutes ago from web

At MountainWest RubyConf- on phone cuz laptop's in car. :( about 5 hours ago from txt

Drivin thru Utah, listening to polygamist jokes. about 12 hours ago from txt

7:28pm Diana Oh, Jay says he wants you to change your profile picture... :):) 7:28pmJennifer why? 7:28pm Diana I don't know, I like it, but he doesn't like it? who knows the mind of a man 7:29pm Jennifer Is it to sexy for him? :):) 7:30pm Diana LOL 7:30pm Jennifer He shouldn't talk though because his profile picture is upclose and personnal. 7:30pm Diana LOL

Diana’s friend is, of course, referring to THIS: