From: "Hal E. Fulton" <hal9000@...>
Date: 2003-05-22T02:59:33+09:00
Subject: How I'd like method-wrapping to work...

OK, I read Matz's blog entries as well as I could.

One thing that occurs to me is that I don't really
want to distinguish between "before" and "after" 
in an artificial way.

Here's my tentative dream of how I'd like to do
this kind of thing in Ruby. (I'm using the keyword
'prior' for lack of anything better right now.)

<fantasy>

class String

  define_hook(:length) do
    puts "I'm calculating the length"
    prior
  end

  define_hook(:upcase) do
    val = prior
    puts "I just did an upcase operation"
    val
  end

  define_hook(:reverse) do
    puts "I'm about to do a reverse operation"
    val = prior
    puts "I just did a reverse"
    val
  end

end

str = "abcde"

x = str.length
puts x

y = str.upcase
puts y

z = str.reverse
puts z

# Output:
# I'm calculating the length
# 5
# I just did an upcase operation
# ABCDE
# I'm about to do a reverse operation
# I just did a reverse
# edcba

</fantasy>

Notes: 

1. Obviously parameter-passing needs to be addressed.
2. It would be nice to get around the return-value
problem (where have I seen this before? 'ensure'?)
3. I've probably overlooked a lot of issues. Please
educate me (Matz, Guy, Dave, David, others...) 


")".intern

Hal