ruby tips and tricks

RUBY Tips & Tricks

Diogo Scudelletti - 2015

WHO Am I?TWITTER: DSCUDELLETTI

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Cautionary WarningThe code in this presentation is to illustrate some awesome features in

ruby, not necessarily they should be used in production.Feel free to use them as your wish though... !


GET LAST EXECTIONbegin raise 'hahahaha'rescue => e # Show the File, Line and Error for the exceptions puts [email protected]

Returns an Array with the Stracktrace["last_exception.rb:2:in `<main>'"]


LISTING LOCAL VARIABLESsome_variable = 1another_variable = 2

puts local_variables.inspect # => [:some_variable, :another_variable]

def something hidden_variable = 3 puts local_variables.inspect # => [:hidden_variable]end

something

puts local_variables.inspect # => [:some_variable, :another_variable]


LISTING THINGS USING GARBAGE COLLECTORList all objects

x=[];ObjectSpace.each_object{|a| x<<a} # => ["RubyVM::InstructionSequence:has_unit_tests...", ...]

List all classesx=[];ObjectSpace.each_object(Class){|a| x<<a}# => ["ARGF.class", "ArgumentError", "Array", "BasicObject", ...]


GSUB + HASH == ❤hash = {"o" => 0, "e" => 3}regexp = Regexp.new(hash.keys.join("|"))

"Love".gsub(regexp, hash) # => "L0v3"


METHODS THE WIN!def some_method(number) "Magic Number: #{number}"end

[1,2,3].map(&method(:some_method))# => ["Magic Number: 1", "Magic Number: 2", "Magic Number: 3"]

PS: It works with Lambdas and Procs


BLOCK ARITYdef some_method(&block) case block.arity when 0 block.call when 1 block.call 'one' when 2 block.call 'one', 'two' when 3 block.call 'one', 'two', 'three' endend

some_method{ |a| puts "#{a}" } # => onesome_method{ |a,b| puts "#{a} #{b}" } # => one twosome_method{ |a,b,c| puts "#{a} #{b} #{c}" } # => one two three


INLINE PRIVATE METHODSclass SomeClass private def some_method puts "XPTO" endend

SomeClass.new.some_method# => NoMethodError: private method `some_method' called


CURRYING FOR THE WIN!calculator = -> (method, a, b) do a.send(method, b)end

calculator.call(:+, 1, 2)calculator.call(:-, 1, 2)

sum = calculator.curry.call(:+)sub = calculator.curry.call(:-)

sum.call(1,2)sub.call(1,2)


DESTRUCTURING ❤a,b,c = [1,2,3]a, = [4,5,6]a, *b = [1,2,3,4]

{ one: [1,2,3], two: [4,5,6] }.each do |key, (first, second, third)| puts "#{key}: #{first} - #{second} - #{third}"end

{ one: [1,2,3], two: [4,5,6] }.each do |key, (head, *tail)| puts "#{key}: #{head} - #{tail}"end

PS Also works with arraysDiogo Scudelletti - 2015

HOW TO CALL A LAMBDA/PROC-> (a){p a}.call("Hello World")-> (a){p a}["Hello World"]-> (a){p a}.("Hello World")

Choose the most readable one!


DUP vs CLONEobject = Object.new.freezeobject.dup.frozen? #=> falseobject.clone.frozen? #=> true


REMOVE vs UNDEFPart 1

class Parent def hello puts "In parent" endendclass Child < Parent def hello puts "In child" endend


REMOVE vs UNDEFPart 2

c = Child.newc.hello # => In child

class Child remove_method :hello # remove from child, still in parentendc.hello # => In parent

class Child undef_method :hello # prevent any calls to 'hello'endc.hello # => undefined method `hello'


METAPROGRAMMING STUFF - REFINEMENTPart 1

class Fixnum def to_hex self.to_s(16) endend

module ExtendFixnum refine Fixnum do def to_octal self.to_s(8) end endend



class Conversor using ExtendFixnum

def self.convert_to_hex 10.to_hex end

def self.convert_to_octal 10.to_octal endend



--- INSIDE CLASS ---HEX:aOCTAL:12--- OUTSIDE CLASS ---HEX:arefinement.rb:35:in `<main>': undefined method `to_octal' for 10:Fixnum (NoMethodError)


FinTWITTER: DSCUDELLETTI

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