Refactoring: Ruby Edition (Patterns)

Front 1

**Extract Method**

You have a code fragment that can be grouped together

Back 1

Turn the fragment into a method whose name explains the purpose of the method

https://gist.github.com/vrybas/1982b803d01dc5e591bf

Front 2

**Inline Method**

A method's is just as clear as its name

Back 2

Put the method's body into the body of its callers and remove the method

Hint 2

#Before:
def get_rating
more_than_five_late_deliveries ? 2 : 1
end

def more_than_five_late_deliveries
@number_of_late_deliveries > 5
end

#After:
def get_rating
@number_of_late_deliveries > 5 ? 2 : 1
end

Front 3

**Inline Temp**

You have a temp that is assingned to once with a simple expression, and the temp
is getting in the way of other reactorings.

Back 3

Replace all references to temp with expression

Hint 3

#Before:
base_price = an_order.base_price
return(base_price > 1000)

#After:
return (an_order.base_price > 1000)

Front 4

**Replace Temp with Query**

You are using temporary variable to hold the result of an expression

Back 4

Extract the expression into a method. Replace all the references to the temp with the expression. The new method can then be used into other methods.

Hint 4

#Before:
def price
base_price = @quantity * @item_price
if base_price > 1000
discount_factor = 0.95
else
discount_factor = 0.98
end
base_price * discount_factor
end

#After:
def price
base_price * discount_factor
end

def base_price
@quantity * @item_price
end

def discount_factor
base_price > 1000 ? 0.95 : 0.98
end

Front 5

**Replace Temp with Chain**

You are using a temporary variable to hold the result of an expression

Back 5

Change the methods to support chaining, thus removing the need for a temp.

Hint 5

#Before:
class Select
def options
@options ||= []
end

def add_option(arg)
options << arg
end
end

select = Select.new
select.add_option(1999)
select.add_option(2000)
select.add_option(2001)
select.add_option(2002)

#After:
class Select
def options
@options ||= []
end

def with_option(option)
select = self.new
select.options << option
select
end

def and(option)
options << option
self
end

select = Select.with_option(1999).and(2000).and(2001).and(2002)