ruby - How to yield 2 blocks in 1 method -

how can yield 2 diferent blocks in same method

the example code:

def by_two(n,a)     yield n     yield end  proc1 = proc {|x| p x * 2} proc2 = proc {|x| x + 100}  by_two(10, 300, &proc1, &proc2) 

the error such -

main.rb:7: syntax error, unexpected ',', expecting ')' by_two(10, 300, &proc1, &proc2) 

any suggestions , wrong? thanks

blocks lightweight way of passing single anonymous procedure method. so, by definition, there cannot 2 blocks passed method. it's not semantically impossible, isn't possible syntactically.

ruby does support first-class procedures in form of procs, however, , since objects other object, can pass many of them want:

def by_two(n, a, proc1, proc2)   proc1.(n)   proc2.(a) end  proc1 = proc {|x| p x * 2} proc2 = proc {|x| x + 100}  by_two(10, 300, proc1, proc2) # 20 # => 400 

since introduction of lambda literals in ruby 1.9, procs syntactically lightweight blocks, there not big difference anymore:

by_two(10, 300, -> x { p x * 2 }, -> x { x + 100 }) # 20 # => 400