Getting the text (source) of a code block

ruby-talk
1

I am writing a ruby DSL and generating code from it. The DSL spec
contains code blocks -- ordinarily these are getting stored as Procs.
However, since I am generating code, I would like to take the source and
print/store it.

It occurs to me that the user should probably store the block as a
heredoc or string, but that could result in code duplication later, and
not allow me to make a change later. Later, I might decide to execute
the app rather than generate code.

So can i extract the source of the block?

Currently my code looks like this:

  def method_missing(id, *args, &block)
    ...
    if block
      hashes[...]=block
    else
      hashes[...]=args
    end
  end

So the hashes object contains a Proc.

···

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2

It occurs to me that the user should probably store the block as a
heredoc or string, but that could result in code duplication later

You can use eval to turn the string into a block:

  class SrcProc
    attr_reader :src
    def initialize(src)
      @src = src
      @proc = eval "lambda #{src}"
    end
    def call(*args,&blk)
      @proc.call(*args,&blk)
    end
    alias : :call
  end

  block = SrcProc.new "{ |x| puts x+x }"
  block["hello,"]
  puts block.src

I believe that going in the opposite direction is much harder (google
for 'parsetree')

···

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