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Ruby Tricks 2
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Michał Łomnicki
November 21, 2012
Technology
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68
Ruby Tricks 2
Michał Łomnicki
November 21, 2012
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Transcript
Ruby Tips & Quirks #2 Michał Łomnicki http://mlomnicki.com
Local variables puts local_variables.inspect y = 4 puts local_variables.inspect
Local variables puts local_variables.inspect # => ["y"] y = 4
puts local_variables.inspect # => ["y"]
Local variables Ruby 1.8 puts local_variables.inspect # => ["y"] y
= 4 puts local_variables.inspect # => ["y"]
Local variables Ruby 1.9 puts local_variables.inspect # => [:y] y
= 4 puts local_variables.inspect # => [:y]
String vs Symbol class String unless instance_methods.include?("camelize") def camelize gsub(/\/(.?)/)
{ "::#{$1.upcase}" } .gsub(/(?:^|_)(.)/) { $1.upcase } end end end
String vs Symbol class String unless instance_methods.any? { |m| m.to_s
== "camelize" def camelize gsub(/\/(.?)/) { "::#{$1.upcase}" } .gsub(/(?:^|_)(.)/) { $1.upcase } end end end
String vs Symbol class String unless instance_methods.method_defined?(:camelize) def camelize gsub(/\/(.?)/)
{ "::#{$1.upcase}" } .gsub(/(?:^|_)(.)/) { $1.upcase } end end end
module functions module Security def generate_password ('a'..'z').sample(8) end end class
User include Security end User.new.generate_password
module functions module Security def generate_password ('a'..'z').sample(8) end end
module functions module Security extend self def generate_password ('a'..'z').sample(8) end
end
module functions module Security extend self def generate_password ('a'..'z').sample(8) end
end Security.generate_password
module functions module Security module_function def generate_password ('a'..'z').sample(8) end end
Security.generate_password
respond_to?(:super) module Sanitizer def save puts "sanitized" super end end
module Persistance def save puts "saved" super end end class User include Persistance include Sanitizer end
respond_to?(:super) module Sanitizer def save puts "sanitized" super end end
module Persistance def save puts "saved" super end end class User include Persistance include Sanitizer end
respond_to?(:super) > User.new.save => sanitized => saved => save: super:
no superclass method save (NoMeth
respond_to?(:super) module Sanitizer def save puts "sanitized" super if respond_to?(:super)
end end module Persistance def save puts "saved" super if respond_to?(:super) end end class User include Persistance include Sanitizer end
respond_to?(:super) module Sanitizer def save puts "sanitized" super if respond_to?(:super)
end end module Persistance def save puts "saved" super if respond_to?(:super) end end class User include Persistance include Sanitizer end
respond_to?(:super) > User.new.save => sanitized
respond_to?(:super) module Sanitizer def save puts "sanitized" super if defined?(super)
end end module Persistance def save puts "saved" super if defined?(super) end end class User include Persistance include Sanitizer end
respond_to?(:super) > User.new.save => sanitized => saved
Class.include module Sanitizer def save puts "sanitized" super if defined(super)
end end module Persistance def save puts "saved" super if defined(super) end end class User include Persistance include Sanitizer end
Class.include module Sanitizer def save puts "sanitized" super if defined(super)
end end module Persistance def save puts "saved" super if defined(super) end end class User include Persistance, Sanitizer end
Class.include > User.new.save => saved => sanitized
Class.include class User include Persistance, Sanitizer end
Class.include class User include Sanitizer, Persistance end
Class.include > User.new.save => sanitized => saved
Block comments =begin Objects don't specify their attributes directly, but
rather infer them from the table definition with which they're linked. Adding, removing, and changing attributes and their type is done directly in the database. =end
Ruby1.9 - each_with_object > (1..5).inject({}) do |i, hsh| hsh[i] =
i*2 hsh end => {1=>2, 2=>4, 3=>6, 4=>8, 5=>10} VS > (1..5).each_with_object({}) do |i, hsh| hsh[i] = i*2 end => {1=>2, 2=>4, 3=>6, 4=>8, 5=>10}
Ruby1.9 - public_send class User protected def destroy puts "destroyed"
end end User.new.public_send(:destroy) NoMethodError: protected method destroy called
Ruby1.9 - ObjectSpace.count_objects ObjectSpace.count_objects { :TOTAL=>76928, :FREE=>549, :T_OBJECT=>1363, :T_CLASS=>1008, :T_MODULE=>38,
:T_FLOAT=>7, :T_STRING=>50339, :T_REGEXP=>234, :T_ARRAY=>7259, :T_HASH=>558, :T_FILE=>16, :T_DATA=>1695, }
Ruby1.9 define_finalizer str = "ruby1.9" ObjectSpace.define_finalizer(str) do |object_id| puts "string
was destroyed id: #{object_id}" end str = nil GC.start => string was destroyed id: -607935038
Ruby1.9 call proc prc = proc { puts "proc called"
} 1) prc.call(1) # 1.8 2) prc[2] # 1.8 3) prc.(3) # new 4) prc.===(4) # new
Ruby1.9 call proc sleep_time = proc do |time| case time.hour
when 0..6 then true else false end end case Time.now when sleep_time puts "go to bed. now!" else puts "work harder" end
Ruby1.9 call proc sleep_time = proc do |time| case time.hour
when 0..6 then true else false end end case Time.now when sleep_time puts "go to bed. now!" else puts "work harder" end sleep_time.===(Time.now)
Questions?