From: ts <decoux@...>
Date: 2000-10-23T23:40:06+09:00
Subject: [ruby-talk:5791] Re: local variables (nested, in-block, parameters,  etc.)

>>>>> "G" == Guy N Hurst <gnhurst@hurstlinks.com> writes:


 The scope of a variable is determined at *compile time*

G> x=9;

  local variable

G> [1,2,3].each{|x~| break if x==2}

  dynamic variable

G> p x	#-> 9
G> p {}::x	#-> 2

 sorry you have lost the dynamic variable.

G> Alternatively, I suppose the same tilde thing could be used for that, too.

G> x=9;
G> [1,2,3].each{|x~| break if x==2}
G> p x	#-> 9
G> p x~	#-> 2

 in this case initialize y (rather than x~) before the each.


G> {|x,y|<a,b> a=x; ....}	# <a,b> in-block only

 Something like this :

pigeon% cat b.rb
#!./ruby
a = 1
b = 2
p "#{a} -- #{b}"
[[3, 4]].each do <a> |b|
      p "#{a} -- #{b}"
end
p "#{a} -- #{b}"
pigeon% b.rb
"1 -- 2"
"3 -- 4"
"1 -- 4"
pigeon% 

G> p {}::a			# but still accessible outside ;-)

 You can't do this I think.

G> I don't think the tilde is so bad, considering its capability...

 You have not resolved the proposition (2), i.e. a *real* 'let' which create a
 block (without a NODE_ITER). My proposition do() is the equivalent of 'let'

 With

  [[3, 4]].each do <a> |b|
      p "#{a} -- #{b}"
  end

 *and*

  do a = a + 2
  end

 You have the proposition (1) *and* the proposition (2)

 I've still not understood the proposition (3) :-(

 proc = lambda(a, b)
 end

 Is this a NODE_ITER or NODE_DEFN (with NODE_ARGS and NODE_SCOPE) ?


Guy Decoux