From: Rudolf Polzer <AntiATField_adsgohere@...>
Date: 2002-12-29T01:13:44+09:00
Subject: block from string

I have a string like

  '|x| 2*x'

What's the simplest way to make a block of this?

I got the idea from writing a rename script that is currently called
like this:

  rename.rb '_.downcase'
  rename.rb '_.gsub(/abcde/, "01234")' *.jpg

And - is it possible to execute this code in the context of the string,
like this:

  rename.rb downcase *.jpg
  rename.rb 'gsub(/abcde/, "01234")' *.jpg
  rename.rb 'self + ".bak"'

It looks like this can be done using instance_eval. It seems to be
working:

  #!/usr/bin/ruby

  expr = ARGV.shift()

  ((ARGV.length() == 0) ? Dir["..?* .[^.]* *"] : ARGV).each() do |_|
    _2 = _.instance_eval(expr)
    puts "%s => %s" % [_, _2]
    File.rename(_, _2) unless File.exists?(_2)
  end

It looks like I don't need the above approach ('|x| 2*x') any more, but
I'm still interested in it - perhaps it's useful somewhere else.

And - note the ugly glob pattern. Is there something cleaner for "take
everything from the current directory except . and .."?


-- 
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Das Erzeugen von C-Code ist sehr fehlerhaft und klappt nur bei ganz
einfachen Programmen.             [Alvar Freude in de.comp.lang.perl.misc]