Mercurial > repos > other > SevenLanguagesInSevenWeeks
view 1-Ruby/code-blocks.rb @ 29:9c7af76fdbd0
Print isn't PrinLn, so add some \n characters to the output
author | IBBoard <dev@ibboard.co.uk> |
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date | Wed, 06 Sep 2017 18:36:02 +0100 |
parents | e58952c15e5e |
children |
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#! /usr/bin/env ruby # Simple passing of code block 3.times { puts 'Repeated string' } # Extending a class class Fixnum def my_times # We're in a number, so store it as an iterator i = self until i == 0 i = i - 1 # Magic happens here! # Yield normally yields a value, but somehow we're executing a blockā¦ yield end end end 3.my_times { puts 'My repeated string' } # Blocks are objects, if you do it right - https://www.ruby-forum.com/topic/49018 my_block = proc { puts 'I am a block' } puts my_block.class # Blocks can be passed around - "&var" says "this is a block" def call_block(&block) block.call end def pass_block(&block) call_block(&block) end pass_block { puts 'Inline block' } pass_block &my_block # Without the "&" we get "wrong number of arguments (1 for 0)" because # a block and an argument are different somehow. This is *not* # because we were trying to call "my_block" and pass what it returned (nil). # I tried. Calling a block definitely needs ".call" # # This page (https://mixandgo.com/blog/mastering-ruby-blocks-in-less-than-5-minutes) # makes it clearer: ANY method can take a block independent of its arguments. # # That means that this works, because we're taking an argument then treating it like # a block: def pass_var_block(block) call_block(&block) end pass_var_block my_block