Can anyone explain this snipped of code from factory_girl
15 views
Skip to first unread message
adam
Jan 16, 2012, 5:02:59 AM1/16/12
to factory_girl
Ive seen the use of the method tap in a couple of spots in the source
code but can't figure out the need to use it. I know it's usually used
when you want to run some code within a long chain of calls ( usually
debugging ) but dont think thats what the reason is here.
#factory.rb
def attributes
compile
AttributeList.new(@name).tap do |list|
processing_order.each do |factory|
list.apply_attributes factory.attributes
end
end
end
and once again in #EvaluatorClassDefiner
def evaluator_class
@evaluator_class ||= Class.new(@parent_class).tap do |klass|
klass.callbacks ||= []
klass.callbacks += @callbacks
klass.attribute_lists ||= []
klass.attribute_lists += [@attributes]
end
end
code but can't figure out the need to use it. I know it's usually used
when you want to run some code within a long chain of calls ( usually
debugging ) but dont think thats what the reason is here.
#factory.rb
def attributes
compile
AttributeList.new(@name).tap do |list|
processing_order.each do |factory|
list.apply_attributes factory.attributes
end
end
end
and once again in #EvaluatorClassDefiner
def evaluator_class
@evaluator_class ||= Class.new(@parent_class).tap do |klass|
klass.callbacks ||= []
klass.callbacks += @callbacks
klass.attribute_lists ||= []
klass.attribute_lists += [@attributes]
end
end
Duncan Beevers
Jan 16, 2012, 11:00:46 AM1/16/12
to factor...@googlegroups.com
Object#tap is used to preserve the return value of the tapped function. Here's the first example, rewritten without tap.
def attributes
compile
list = AttributeList.new(@name)
processing_order.each do |factory|
list.apply_attributes factory.attributes
end
list
end
In both forms of this function the final value of `list` has to be returned. By using `tap` we can avoid this and just rely on the return value of AttributeList.new while still doing something useful with the intermediate value of `list`.
Here's a quick write-up on the functionality in case this explanation wasn't clear.
- Duncan
--
Individuals over processes. Interactions over tools. Agile Rails training from thoughtbot, the makers of Clearance, Shoulda, & Factory Girl:
http://thoughtbot.com/services/training
You received this message because you are subscribed to the "factory_girl" mailing list.
To post to this group, send email to factor...@googlegroups.com
To unsubscribe from this group, send email to
factory_girl...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/factory_girl?hl=en
Dan Tripp
Jan 16, 2012, 11:06:05 AM1/16/12
to factor...@googlegroups.com
I thought this explanation was pretty concise/useful:
- Dan
Dan Tripp
Jan 16, 2012, 11:07:11 AM1/16/12
to factor...@googlegroups.com
+1
Reply all
Reply to author
Forward
0 new messages