Callable and runnable objects in ruby

Callable and runnable objects in ruby

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  Callable and Runnable objectsin Ruby. By: Rahul Bajaj @rabajaj_
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  About Me! AssociateSoftware Engineer @ Red Hat Follow me: Twitter: @rabajaj_ Github: rahulbajaj0509 @rabajaj_
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  Agenda ● Proc Objects ●Lambdas ● Method Objects @rabajaj_ 1. Callable objects in Ruby: 2. Threads in Ruby
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  Blocks Can you dosomething like this? block = do |test| puts test end 3.upto(8) block @rabajaj_
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  Obviously not! But why? ●Blocks are not objects ● They can not be stored in to a variable Does ruby have a solution for this? @rabajaj_
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  Procs foo=Proc.new do |test| putstest end 3.upto(8) { foo.call("hello world") } @rabajaj_
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  Procs ● Basics ofcreating and using Procs. ● Relationship between procs and blocks. ● Procs as closures ● Proc parameters & arguments @rabajaj_
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  Relationship between procs andblocks. def capture_block(&block) block.call end capture_block { puts "Inside the block" } Block to Proc Using Procs for Blocks def capture_block(&block) block.call end p = Proc.new { puts “This proc arg will serve as code block” } capture_block(&p) @rabajaj_ Inside the block This proc arg will serve as code block
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  closures def call_some_proc(pr) a =“irrelevant ‘a’ in method scope” puts a pr.call end a = “ ‘a’ to be used in Proc block” pr = Proc.new { puts a } pr.call call_some_proc(pr) ‘a’ to be used in Proc block irrelevant ‘a’ in method scope ‘a’ to be used in Proc block @rabajaj_
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  Proc parameters & arguments pr= Proc.new { |x| puts “Called with argument #{x}”} pr.call(100) Called with argument 100 >> pr = Proc.new { |x| puts x} => #<Proc:975676592328@> >> pr.call nil >> pr.call(1,2,3) 1 @rabajaj_
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  Lambdas The lambda methodreturns a Proc object! ● Basic creation of Lambda. ● Difference between Proc and Lambda: a. Calling b. Return method c. Arguments @rabajaj_
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  Return statement: def return_test l=lambda{return} l.call puts“Still here!” p = Proc.new { return } p.call puts “You won’t see this” end return_test Still here! Lambdas Calling: lam = lambda { puts “A Lambda!” } lam.call A Lambda! @rabajaj_
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  Lambdas continued.. Arguments: >> lam =lambda { |x| puts x } => #<Proc:093846783543@> >>lam.call(1) 1 >>lam.call ArgumentError: wrong number of arguments @rabajaj_
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  Threads Thread creation Thread.new do puts"Starting the thread" sleep 1 puts "At the end of the thread" end puts "Outside the thread" @rabajaj_
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  Threads continued.. t = Thread.newdo puts "Starting the thread" sleep 1 puts "At the end of the thread" end puts "Outside the thread" t.join @rabajaj_
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  puts "Trying toread in some files..." t = Thread.new do (0..2).each do |n| begin File.open("part0#{n}") do |f| text << f.readlines end rescue Errno::ENOENT puts "Message from thread: Failed on n=#{n}" Thread.exit End end end t.join puts "Finished!" @rabajaj_ Trying to read in some files... Message from thread: Failed on n=1 Finished! THREAD TERMINATION (KILLING) The idea is to read the contents of the three files (part00, part01, part02) into the string text. If any of the files isn’t found, the thread terminates.
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  Thank you ! @rabajaj_