Autoloading objects — Ruby equivalent for PHP5 "__autoload

[Naum T.]

Does there exist a Ruby equivalent to PHP5 "magic" __autoload method
that spares the developer from detailing a list of "require" statements?
http://us2.php.net/autoload

Or is this something that a homebrewed solution is necessary? Like
catching the exception and testing for file existence, etc.… or is there
a gem/extension featuring this functionality?

 

[Marcin Mielżyński]

Does there exist a Ruby equivalent to PHP5 "magic" __autoload method
that spares the developer from detailing a list of "require" statements?
http://us2.php.net/autoload

Or is this something that a homebrewed solution is necessary? Like
catching the exception and testing for file existence, etc.… or is there
a gem/extension featuring this functionality?

Sure there is ;D

Kernel#autoload:
http://ruby-doc.org/core/classes/Kernel.html#M002963

and:

Module#autoload:
http://ruby-doc.org/core/classes/Module.html#M001061

lopex

 

[Mat Schaffer]

Does there exist a Ruby equivalent to PHP5 "magic" __autoload method
that spares the developer from detailing a list of "require" =20
statements?
http://us2.php.net/autoload

Or is this something that a homebrewed solution is necessary? Like
catching the exception and testing for file existence, etc.=85 or is =20=

there
a gem/extension featuring this functionality?

const_missing is a little more like PHP's __autoload function.

The following, for example will attempt to just do: require <object =20
name> in the event it can't find the class.

def Object.const_missing name
require name.to_s.downcase
const_get(name)
end

I've never used it though, so anyone can feel free to correct me for =20
any gotchas that I'm not aware of.
-Mat=

 

[Alex Young]

Sure there is ;D

Kernel#autoload:
http://ruby-doc.org/core/classes/Kernel.html#M002963

and:

Module#autoload:
http://ruby-doc.org/core/classes/Module.html#M001061

That's not quite it. You need to call Module.autoload yourself. PHP's
autoload is called by the interpreter to perform the inclusion. You
could use const_missing to get a similar functionality, though...

def Object.const_missing(name)
load name.to_lower + ".rb"
end

That's got a few rough edges, though, to put it mildly...

 

[Alex Young]

Alex Young wrote:

def Object.const_missing(name)
load name.to_lower + ".rb"
end

That's got a few rough edges, though, to put it mildly...

I mean, besides the fact that it won't work, unlike Mat's. Should have
tested that one...

 

[Naum T.]

That's seems to be the ticket.

Knew about ruby autoload, but you have to specify up front each
module/file whereis PHP5, it's (but named "__autoload") a "catch all".

One solution is to glob the directory (where I have my classes stored)
and issue autoload for each result:

# assumes my custom classes begin with upper case
Dir.glob('[A-Z]*.rb').each do |f|
rsym = f.gsub("[.]rb$", '')
autoload#{rsym}, f)
end

 

[Matthew Harris]

You would probably want to use some metaprogramming to define
const_missing recursively on currently defined constants, and then
it's pretty much the same as PHP's __autoload().

 

[Gonzalo Garramuno]

Naum T. escribió:

Does there exist a Ruby equivalent to PHP5 "magic" __autoload method
that spares the developer from detailing a list of "require" statements?
http://us2.php.net/autoload

Or is this something that a homebrewed solution is necessary? Like
catching the exception and testing for file existence, etc.… or is there
a gem/extension featuring this functionality?

def Object.const_missing elem
require elem.to_s
end

a = A.new

PS. I would advise *NOT* doing this kind of thing, thou. It can make
your code much harder to debug for other developers.

 

[Mat Schaffer]

Naum T. escribi=F3:

def Object.const_missing elem
require elem.to_s
end

a =3D A.new

PS. I would advise *NOT* doing this kind of thing, thou. It can make
your code much harder to debug for other developers.

you need

def Object.const_missing elem
require elem.to_s const_get(elem)
end

To make this work, otherwise the 'A' in A.new becomes the return =20
value of 'require elem.to_s'
-Mat=

 

[Matthew Harris]

I do hope you know that there's a lot of things in Ruby that makes a
developer's debugging life quite hard, but the point is that it's
convenient to have these sort of solutions.

Naum T. escribi=F3:

def Object.const_missing elem
require elem.to_s
end

a =3D A.new

PS. I would advise *NOT* doing this kind of thing, thou. It can make
your code much harder to debug for other developers.

--=20
Matt

 

[Piotr Biedruna]

const_missing is a little more like PHP's __autoload function.

The following, for example will attempt to just do: require <object
name> in the event it can't find the class.

def Object.const_missing name
require name.to_s.downcase
const_get(name)
end

Well, th const_missing sollution does work, but only in scripts called
directly in shell by 'ruby' executable. When using it in script called
in browser i get:

[Tue Mar 20 16:56:49 2007] [error] mod_ruby: error in ruby
[Tue Mar 20 16:56:49 2007] [error] mod_ruby:
/home/services/httpd/html/TRON/ruby/index.rb:11: uninitialized constant
#<Module:0xb6a6ea30>::Test (NameError)
[Tue Mar 20 16:56:49 2007] [error] mod_ruby: from
/usr/lib/ruby/1.8/apache/ruby-run.rb:38:in `load'
[Tue Mar 20 16:56:49 2007] [error] mod_ruby: from
/usr/lib/ruby/1.8/apache/ruby-run.rb:38:in `handler'

Got apache 2.2 with mod_ruby configured as follows:

LoadModule ruby_module modules/mod_ruby.so

<IfModule mod_ruby.c>

AddType text/html .rb

RubyRequire apache/ruby-run

<Files *.rb>
Options +ExecCGI
SetHandler ruby-object
RubyHandler Apache::RubyRun.instance
</Files>

</IfModule>

What i`ve been trying to get is an equivalent of PHP __autoload()
routine working under both shell execution and apache handler. Know any?

 

[Chris Carter]

const_missing is a little more like PHP's __autoload function.

The following, for example will attempt to just do: require <object
name> in the event it can't find the class.

def Object.const_missing name
require name.to_s.downcase
const_get(name)
end

Well, th const_missing sollution does work, but only in scripts called
directly in shell by 'ruby' executable. When using it in script called
in browser i get:

[Tue Mar 20 16:56:49 2007] [error] mod_ruby: error in ruby
[Tue Mar 20 16:56:49 2007] [error] mod_ruby:
/home/services/httpd/html/TRON/ruby/index.rb:11: uninitialized constant
#<Module:0xb6a6ea30>::Test (NameError)
[Tue Mar 20 16:56:49 2007] [error] mod_ruby: from
/usr/lib/ruby/1.8/apache/ruby-run.rb:38:in `load'
[Tue Mar 20 16:56:49 2007] [error] mod_ruby: from
/usr/lib/ruby/1.8/apache/ruby-run.rb:38:in `handler'

Got apache 2.2 with mod_ruby configured as follows:

LoadModule ruby_module modules/mod_ruby.so

<IfModule mod_ruby.c>

AddType text/html .rb

RubyRequire apache/ruby-run

<Files *.rb>
Options +ExecCGI
SetHandler ruby-object
RubyHandler Apache::RubyRun.instance
</Files>

</IfModule>

What i`ve been trying to get is an equivalent of PHP __autoload()
routine working under both shell execution and apache handler. Know any?

ri Kernel.autoload