How to initialize a class in a block in Ruby?

Question

I cannot determine the correct block initialization

class Foo attr_accessor :bar end obj = Foo.new do |a| a.bar = "baz" end puts obj.bar 

Expect "baz" instead get nil

What is the correct spell for block class initializers in ruby?

Answer 1

Try again:

 class Foo attr_accessor :bar end obj = Foo.new.tap do |a| a.bar = "baz" end puts obj.bar 

Answer 2

Another way to make a block initializer is to write it yourself:

 class Foo attr_accessor :bar def initialize yield self if block_given? end end 

And later use it:

 foo = Foo.new do |f| f.bar = true end 

My two cents.

Answer 3

I don't think new can take a block. Never seen him anyway. Why do you want to initialize a block? You can always do obj = foo.new.tap do |a| ... obj = foo.new.tap do |a| ... if you really need a block

Answer 4

in fact, you have a constructor for these purposes:

 class Foo attr_accessor :bar def initialize(bar = "baz") @bar = bar end end