Autorequire.rb


#1

just hacked this out - can anyone see holes in it?

 harp:~ > cat autorequire.rb
 class Module
   alias_method "const_missing!", "const_missing"
   def const_missing c
     lib4 = lambda{|k| k.to_s.downcase.gsub(%r/::/, 

File::SEPARATOR)}
lib = Object == self ? lib4[c] : lib4["#{ name }::#{ c }"]
begin; require lib; rescue LoadError; end
const_missing! c unless const_defined? c
const_get c
end
end

 if $0 == __FILE__
   p Object
   p CGI
   p CGI::Session
   p PStore
   p K
 end



 harp:~ > ruby autorequire.rb
 Object
 CGI
 CGI::Session
 PStore
 autorequire.rb:7:in `const_missing': uninitialized constant K 

(NameError)
from autorequire.rb:17

regards.

-a


#2

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Depending on how smart you want it to be it will fail on stdlib’s that
don’t follow a consistent downcase/spelling naming
convention, ie: ostruct => OpenStruct

It doesn’t work with files which don’t have a toplevel file to include,
like ‘net/ssh’. There is no ‘net’ file to load like there
is with ‘cgi’ in ‘cgi/session’. Although I can’t think of a way OTOH to
get around this with const_missing, since you’ll never see
the SSH part of Net::SSH because it will fail on Net.

Zach

removed_email_address@domain.invalid wrote:

    lib = Object == self ? lib4[c] : lib4["#{ name }::#{ c }"]
  p PStore
autorequire.rb:7:in `const_missing': uninitialized constant K

(NameError)
from autorequire.rb:17

regards.

-a

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

iD8DBQFENpRwMyx0fW1d8G0RAlDMAJ9GRGbwAEG3nbyH2t4FYdVx7WmVIwCdGAdb
IN5Qznuop52w7ClovrY7mvM=
=AW3I
-----END PGP SIGNATURE-----


#3

On Sat, 8 Apr 2006, zdennis wrote:

Zach
this is a possible workaround - it’s broken for some cases now but i’m
just
trying to show it’s possible :

 harp:~ > ruby a.rb

 {"Net"=>"ConstProxy(Net)"}
 {"Net::FTP"=>Net::FTP}



 harp:~ > cat a.rb

 require 'pp'

 autorequire 'Net::FTP' => 'net/ftp'

 pp 'Net' => Net
 pp 'Net::FTP' => Net::FTP



 BEGIN {
   require 'enumerator'

   class Module
     alias_method "const_missing!", "const_missing"

     def const_missing c
       c = c.to_s

       if autorequire.has_key? c
         obj = autorequire[c]
         cp = obj.respond_to?('ancestors') and 

obj.ancestors.include?(ConstProxy)
if cp
return obj
else
libs = obj
libs.each{|lib| begin; require lib; rescue LoadError;
end}
end
else
lib4 = lambda{|k| k.to_s.downcase.gsub(%r/::/,
File::SEPARATOR)}
lib = Object == self ? lib4[c] : lib4["#{ name }::#{ c }"]
begin; require lib; rescue LoadError; end
end

       if ancestors.include?(ConstProxy)
         to_const.const_get c
       else
         const_missing! c unless const_defined? c
         const_get c
       end
     end

     def autorequire c = nil, *libs
       if c
         h = Hash === c ? c : {c => libs}
         h.each do |c,libs|
           if c =~ %r/::/
           # hack for two deep nesting only
             k,v = c.split %r/::/
             cp = ConstProxy(k)
             autorequire[k] = cp
             cp.autorequire[v] = libs
           else
             autorequire[c.to_s] = [libs].flatten
           end
         end
         self
       else
         @autorequire ||= {}
       end
     end
   end

   module ConstProxy
     def self.new name
       name = name.to_s
       raise ArgumentError unless name =~ %r/^[A-Z]/
       Module.new do
         include ConstProxy
         singleton_klass =
           class << self; self; end
         singleton_klass.module_eval do
           define_method('name'){ name }
           define_method('to_s'){ "ConstProxy(#{ name })" }
           define_method('inspect'){ "\"#{ to_s }\"" }
           define_method('to_const'){ Object.const_get(name) }
         end
       end
     end
     module ::Kernel
       def ConstProxy(*a, &b) ConstProxy.new(*a, &b) end
     end
   end

   class Object
     def autorequire(*a, &b)
       self.class.autorequire(*a, &b)
     end
   end
 }

i’ll keep hacking on it and try to release something soon…

-a