What's the difference between a lambda, a block and a proc?

  1. The difference between Blocks and Procs
    1. Procs is an Object, but Block is not an object, it is just a code snippet
    2. Each method can only pass one code segment at most, but can pass multiple Proc
  2. Similarities and differences between Proc and Lambda

proc = Proc.new {puts "hello world"}
lambda = lambda {puts "hello world"}

proc.class  # rerturn 'Proc'
lambda.class # return 'Proc'


As can be seen from the above, in fact, Proc and lambda are both Proc objects.

lambdaWill check the number of parameters but procnot

lam = lambda { |x| puts x}
lam.call(2)  # print 2
lam.call  # Argument Error: wrong number of arguments (0 for 1)
lam.call(1,2) # Argument Error: wrong number of arguments (2 for 1)

pro = Proc.new {|x| puts x}
proc.call(2)  # print 2
proc.call    # return nil
proc.call(1,2) # print 1


lambda And proc the meaning of the 'return' key is not the same, but proc the return only call in the method body

def lambda_test
  lam = lambda { return }
  lam.call
  puts "hello"
end

lambda_test   # puts 'hello'

def proc_test
  pro = Proc.new {return}
  proc.call
  puts 'hello'
end

proc_test  # return nil  hello


Refer: What Is the Difference Between a Block, a Proc, and a Lambda in Ruby?


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