访问块内定义的变量

Question

I have this snippet:

class MyClass
    def self.callWithBlock (&block)
        print block.blockVar
    end
end

MyClass::callWithBlock do
    blockVar = 'Hello'
end

which gives me an error:

in `callWithBlock': undefined method `blockVar' for #<Proc:0x000000017ed168@./block-test.rb:9> (NoMethodError)
    from ./block-test.rb:9:in `<main>'

How to access this blockVar ?

Answer 1

If you add binding at the end of the block, that would become the result of call -ing the block, and you can eval whatever local variables assigned in that block within the context of the binding.

class MyClass
  def self.callWithBlock (&block)
    print block.call.eval('blockVar')
  end
end

MyClass::callWithBlock do
  blockVar = 'Hello'
  binding
end
# => Hello