From: Intransition <transfire@...>
Date: 2011-11-07T07:35:13+09:00
Subject: Tricky DSL, how to do it?

------=_Part_276_31929973.1320618910818
Content-Type: multipart/alternative; 
	boundary="----=_Part_277_28280983.1320618910823"

------=_Part_277_28280983.1320618910823
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

I'd want to write a DSL such that a surface method_missing catches 
undefined methods and records the blocks that they define e.g.

  foo do
    puts "foo"
  end

So I would end up with:

  { :foo=>#<Proc ...> }

Presently I have something like this:

  #
  class Evaluator < BasicObject
    def initialize(&block)
      @__config__ = {}
      instance_eval(&block) if block
    end

    def __config__
      @__config__
    end

    def method_missing(sym, *args, &block)
      @__config__[sym] = block
    end 
  end

However when I call on a block I want it to evaluate as if in the defining 
context (in this case toplevel), not inside the "DSL" class that evaluated 
via method_missing. 

  e = Evaluator.new do
    foo do
      puts "foo"
    end
  end

  e.__config__[:foo].call

Instead of what I want, I get a method missing error for #puts.

Any ideas?

------=_Part_277_28280983.1320618910823
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

I'd want to write a DSL such that a surface method_missing catches undefine=
d methods and records the blocks that they define e.g.<div><br></div><div>&=
nbsp; foo do</div><div>&nbsp; &nbsp; puts "foo"</div><div>&nbsp; end</div><=
div><br></div><div>So I would end up with:</div><div><br></div><div>&nbsp; =
{ :foo=3D&gt;#&lt;Proc ...&gt; }</div><div><br></div><div>Presently I have =
something like this:<br></div><div><br></div><div><div>&nbsp; #</div><div>&=
nbsp; class Evaluator &lt; BasicObject</div><div>&nbsp; &nbsp; def initiali=
ze(&amp;block)</div><div>&nbsp; &nbsp; &nbsp; @__config__ =3D {}</div><div>=
&nbsp; &nbsp; &nbsp; instance_eval(&amp;block) if block</div><div>&nbsp; &n=
bsp; end</div><div><br></div><div>&nbsp; &nbsp; def __config__</div><div>&n=
bsp; &nbsp; &nbsp; @__config__</div><div>&nbsp; &nbsp; end</div><div><br></=
div><div>&nbsp; &nbsp; def method_missing(sym, *args, &amp;block)</div><div=
>&nbsp; &nbsp; &nbsp; @__config__[sym] =3D block<br></div><div>&nbsp; &nbsp=
; end&nbsp;</div><div>&nbsp; end</div></div><div><br></div><div>However whe=
n I call on a block I want it to evaluate as if in the defining context&nbs=
p;(in this case toplevel), not inside the "DSL" class that evaluated via me=
thod_missing.&nbsp;</div><div><br></div><div>&nbsp; e =3D Evaluator.new do<=
/div><div><div style=3D"border-style: initial; border-color: initial; ">&nb=
sp; &nbsp; foo do</div><div style=3D"border-style: initial; border-color: i=
nitial; ">&nbsp; &nbsp; &nbsp; puts "foo"</div><div style=3D"border-style: =
initial; border-color: initial; ">&nbsp; &nbsp; end</div></div><div>&nbsp; =
end<br></div><div><br></div><div>&nbsp; e.__config__[:foo].call</div><div><=
br></div><div>Instead of what I want, I get a method missing error for #put=
s.</div><div><br></div><div>Any ideas?</div>
------=_Part_277_28280983.1320618910823--

------=_Part_276_31929973.1320618910818--