是否可以使用do块初始化Ruby哈希？

Question

I love the feel of the Ruby do ... end block, and I would love to be able to use it to initialize a hash. I'm aware of the curly brace construction, eg

h = {
  :a => 10,
  :b => 20
}

But I was wondering if there's a way to do the same sort of thing with a do block, eg

h_keys = keys do
  :a => 10,
  :b => 20
end

Edit

Let me be clearer: I do understand that a hash literal is not a block, and I have a pretty good grasp of the internals of a block. What I'm wondering is more along the lines of this:

Is it possible, perhaps via (but not constrained to) some clever metaprogramming method, to write a function such that a block passed into it is interpreted as a hash?

Answer 1

This is a bit similar to your desired sample code, though the do ... end is gone:

 def keys(x); x; end
 h = keys a: 1, b: 2

Unfortunately keys do a: 1, b: 2 end doesn't match Ruby's grammar. Naturally, you could still write a preprocessor which would run over a source file, rewrite your added syntax to standard Ruby syntax, then feed it to the interpreter. That would be more than a little crazy, but if you want to do it, more power to you...