Cutter
¶ ↑
Two-methods-gem I use a lot for simple debugging & performance measuring purposes.
#inspect
method shines when doing reverse engineering, it is especially useful, when it is needed to quickly hack on someone else's code. Also, it is very easy to become 'someone else' for self, when dealing with own code, if it was written very long time ago.
Besides that #stamper
allows doing performance measuments in a handy manner, it can be used to create quick and neat demonstrations of how particular pieces of Ruby code perform.
The one interesting possible usage of #stamper
is performance optimization of templates on Rails View Layer, because it often takes a large load impact (compared to M and C layers) because of Rails lazy-evaluation mechanisms.
Prerequisites¶ ↑
It works on 1.8.7, 1.9.3, JRuby and Rubinius.
Installiation¶ ↑
Include it into Gemfile:
group :development, :test do gem 'cutter' end
Cutter::Inspection
¶ ↑
I) inspect!¶ ↑
Insert #inspect!
method into any of your methods:
def your_method *your_args # ... inspect! {} # curly braces are important - they capture original environment! # or # iii {} as an alias # ... end # your_method(1,"foo",:bar) => # method `your_method' # variables: # your_args: [1, "foo", :bar]
It gives simple but nice trace for inspection: method's name and args that were passed to method.
With inspect!(:instance) {}
we also see instance variables:
def your_method a, b @instance_var = "blip!" inspect!(:instance) {} end # your_method 1, 2 # method: `your_method' # called from class: RSpec::Core::ExampleGroup::Nested_1::Nested_1 # local_variables: # a: 1 # b: 2 # instance_variables: # @instance_var: blip!
With inspect!(:self) {}
we have self#inspect
of class to which method belongs to:
def your_method name, *args # ... inspect!(:self) {} end # your_method(1,2,3,4,5) => # method: `your_method' # called from class: SelfInspectDemo # variables: # name: 1 # args: [2, 3, 4, 5] # block: # self inspection: # #<SelfInspectDemo:0x82be488 @variable="I'm variable">
Option :caller
gives us caller methods chain:
def your_method name, *args # ... inspect!(:caller) {} end # your_method(1,2,3,4,5) => # method: `your_method' # called from class: RSpec::Core::ExampleGroup::Nested_1::Nested_1 # variables: # name: 1 # args: [2, 3, 4, 5] # block: # caller methods: # /home/stanislaw/_work_/gems/cutter/spec/inspection/demo_spec.rb:33:in `your_method' # /home/stanislaw/_work_/gems/cutter/spec/inspection/demo_spec.rb:40:in `block (3 levels) in <top (required)>' # /home/stanislaw/.rvm/gems/ruby-1.9.2-p180@310/gems/rspec-core-2.6.4/lib/rspec/core/example.rb:48:in `instance_eval'
And finally inspect!(:max) {}
produces maximum information: options :instance
, :self
, :caller
are included and Ruby's ordinary #inspect
method is called on every variable.
def your_method *args inspect!(:max) {} end # maximal(1, :two, "three", :four => 5) => # # method: `your_method' (maximal tracing) # called from class: RSpec::Core::ExampleGroup::Nested_1::Nested_1 # local_variables: # args: [1, :two, "three", {:four=>5}] # instance_variables: # @example: #<RSpec::Core::Example:0xa1d378 > # ... # self inspection: # #<RSpec::Core::ExampleGroup::Nested_1::Nested_1:0x9e5f8f4 # ... # caller methods: # /home/stanislaw/work/gems/cutter/spec/inspection/demo_spec.rb:28:in `maximal' # /home/stanislaw/work/gems/cutter/spec/inspection/demo_spec.rb:54:in `block (3 levels) in <top (required)>' # ...
If you want all #inspect!
methods fall silent at once, use
Cutter::Inspection.quiet!
To make them sound again do
Cutter::Inspection.loud!
Three-letters methods¶ ↑
class Object def rrr object = nil raise object.inspect end def ppp object = nil puts object.inspect end def lll object = nil Rails.logger.info object.inspect end if defined? Rails end
iii¶ ↑
Instead of #inspect!
you can use #iii
- just an alias more convenient for typing.
Finally, you have a group of 4 three-letters methods in your every day debugging workflow.
II) Cutter::Stamper
¶ ↑
Acts as benchmark {}
in Rails or Benchmark.measure {}
in common Ruby, but with stamps in any position in block executed.
It is much simpler to write Stamper with Stamps than all these Measure-dos.
Minimal stamper¶ ↑
!
method is just an alias for stamp
, use whatever you like:
puts "Minimal stamper" stamper do stamp sleep 0.2 stamp! sleep 0.2 stamp! end
Will produce:
Minimal stamper no name ------- stamp: 0 ms stamp: 200 ms stamp: 400 ms ------- 400ms
Stamper with named stamps¶ ↑
puts "Now with named stamps" Cutter::Stamper.scope :testing_method => "Demonstration of named stamping" do |tm| tm.msg _1: "first piece" tm.msg _2: "second piece" end Cutter::Stamper.scope :inner_scope => "Now internal things" do |i| i.msg first: "I'm the first inner stamp" end stamper :testing_method do |tm| sleep 0.3 tm.stamp! :_1 # The old form of calling #stamp! on yielded scope variable sleep 0.3 stamper :inner_scope do |i| sleep 0.2 i.stamp! :first sleep 0.2 i.stamp! "Stamp with custom text" end tm.stamp! :_2 end
will result in
Now with named stamps Demonstration of named stamping ------------------------------- stamp: 300 ms first piece Now internal things ------------------- stamp: 201 ms I'm the first inner stamp stamp: 401 ms Stamp with custom text ------------------- 401ms stamp: 1001 ms second piece ------------------------------- 1001ms
Stamper with :capture => true
option¶ ↑
Use it to hide the output of piece you are benchmarking.
require 'cutter' N = 100000 result = [] EMB = "String to embed" result << stamper(:capture => true) do N.times do puts "#{EMB}\n" end end result << stamper(:capture => true) do N.times do printf "#{EMB}\n" end end result << stamper(:capture => true) do N.times do print "#{EMB}\n" end end puts result.inspect
Notes¶ ↑
-
Both
#inspect! {}
and#stamper
methods colorize their output. You can seelib/cutter/colored_output.rb
file to understand how it is done. I will really appreciate any suggestions of how current color scheme can be improved.
Specs and demos¶ ↑
Clone it
$ git clone https://github.com/stanislaw/cutter $ cd cutter
Specs are just
rake
See demos
rake demo
Contributors¶ ↑
-
Stanislaw Pankevich
-
Kristian Mandrup
Copyright¶ ↑
Copyright © 2011 Stanislaw Pankevich