Stuck with modules/classes/inheritance

ruby-talk
1

given:

test.rb :

require 'b'

b = B.new

lib/base.rb:

module A
  class Base
  end
end

lib/b.rb:

module A
  class B < Base
  end
end

Why do I get

./lib/b.rb:2: uninitialized constant A::Base (NameError)
        from test.rb:1:in `require'
        from test.rb:1

?

This is a stripped down version of what I want to do (ie organize my code into a module, but still keep classes in separate files, have a base class and inherit).

It's probably something trivial, but at the moment I'm stuck - any help would be (as always) greatly appreciated

Kev

2

given:

test.rb :

require 'b'

b = B.new

b = A::B.new

lib/base.rb:

module A
class Base
end
end

lib/b.rb:

require 'base'

module A
class B < Base
end
end

Why do I get

./lib/b.rb:2: uninitialized constant A::Base (NameError)
       from test.rb:1:in `require'
       from test.rb:1

?

This is a stripped down version of what I want to do (ie organize my code into a module, but still keep classes in separate files, have a base class and inherit).

It's probably something trivial, but at the moment I'm stuck - any help would be (as always) greatly appreciated

Also you can get away with less indentation:

$ cat base.rb
module A; end

class A::Base
end
$ cat b.rb
require 'base'

class A::B < A::Base
end

···

On Oct 27, 2005, at 9:35 PM, Kev Jackson wrote:

--
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E 7C11 332A 551C 796C 9F04

3

Selon Kev Jackson :

given:

test.rb :

require 'b'

b = B.new

lib/base.rb:

module A
class Base
end
end

lib/b.rb:

module A
class B < Base
end
end

Why do I get

./lib/b.rb:2: uninitialized constant A::Base (NameError)
       from test.rb:1:in `require'
       from test.rb:1

?

In lib/b.rb, you need to write:
require "base"
module A
  class B < Base
  end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

···

--
Christophe Grandsire.

http://rainbow.conlang.free.fr

You need a straight mind to invent a twisted conlang.

4

Kev Jackson wrote:

given:

test.rb :

require 'b'

b = B.new

lib/base.rb:

module A
  class Base
  end
end

lib/b.rb:

module A
  class B < Base
  end
end

Why do I get

/lib/b.rb:2: uninitialized constant A::Base (NameError)
        from test.rb:1:in `require'
        from test.rb:1

?

This is a stripped down version of what I want to do (ie organize my
code into a module, but still keep classes in separate files, have a
base class and inherit).

It's probably something trivial, but at the moment I'm stuck - any help
would be (as always) greatly appreciated

Kev

Hi Kev,

require 'b' loads /and runs/ b.rb immediately.
You have at the top:

  module A
    class B < Base
    end
  end

Base is defined later, so you need to organise the require order (?).
Then b = A::B.new (as Eric said)

HTH,

daz

5

In lib/b.rb, you need to write:

require "base"
module A
class B < Base
end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

require 'base'

causes

./lib/b.rb:1:in `require': No such file to load -- base (LoadError)
        from ./lib/b.rb:1
        from test.rb:1:in `require'
        from test.rb:1

which is weird as I have done this before with other files, it's just this one that it won't find

6

In lib/b.rb, you need to write:

require "base"
module A
class B < Base
end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

require 'base'

require 'lib/base' then

···

On Oct 27, 2005, at 9:51 PM, Kev Jackson wrote:

causes

./lib/b.rb:1:in `require': No such file to load -- base (LoadError)
       from ./lib/b.rb:1
       from test.rb:1:in `require'
       from test.rb:1

which is weird as I have done this before with other files, it's just this one that it won't find

--
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E 7C11 332A 551C 796C 9F04

7

Kev Jackson wrote:

In lib/b.rb, you need to write:

require "base"
module A
class B < Base
end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

require 'base'

causes

./lib/b.rb:1:in `require': No such file to load -- base (LoadError)
       from ./lib/b.rb:1
       from test.rb:1:in `require'
       from test.rb:1

which is weird as I have done this before with other files, it's just this one that it won't find

in fact from test.rb, I can require 'lib/base', but from b.rb I can't require 'base' (with b.rb and base.rb in the same directory) - this is very strange behaviour

Kev

8

Eric Hodel wrote:

···

On Oct 27, 2005, at 9:51 PM, Kev Jackson wrote:

In lib/b.rb, you need to write:

require "base"
module A
class B < Base
end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

require 'base'

require 'lib/base' then

Thanks, this fixes it - but the actual path 'lib/base' is incorrect in the context of the file b.rb (b.rb is in the same directory as base.rb, therefore the line should be require 'base' no?)

Kev

9

Selon Kev Jackson <kevin.jackson@it.fts-vn.com>:

>
> require 'base'
>
> causes
>
> ./lib/b.rb:1:in `require': No such file to load -- base (LoadError)
> from ./lib/b.rb:1
> from test.rb:1:in `require'
> from test.rb:1
>
> which is weird as I have done this before with other files, it's just
> this one that it won't find
>
in fact from test.rb, I can require 'lib/base', but from b.rb I can't
require 'base' (with b.rb and base.rb in the same directory) - this is
very strange behaviour

Oops! Of course. "require"'s lookup system bit me again. IIRC it uses
$LOAD_PATH, which contains the usual standard lib directory roots, as well as
the directory of the file first run by Ruby (AFAIK). It *doesn't* contain the
path of library files you may also require. So you have to do require
'lib/base' everywhere.

Is there a good reason for this behaviour? There was a RCR to make the require
load path relative to the currently executing file (rather than only the
originally executing file), but it is branded 'obsolete' and I haven't seen it
rewritten, not even in the rejected RCRs. It's currently here:
http://www.rcrchive.net/rcr/show/170
Wouldn't it be a good idea to revive it?

···

--
Christophe Grandsire.

http://rainbow.conlang.free.fr

It takes a straight mind to create a twisted conlang.

10

The load path works from Dir.pwd, not the paths of the files you require.

ruby -Ilib will allow things to Just Work.

···

On Oct 27, 2005, at 9:59 PM, Kev Jackson wrote:

Eric Hodel wrote:

On Oct 27, 2005, at 9:51 PM, Kev Jackson wrote:

In lib/b.rb, you need to write:

require "base"
module A
class B < Base
end
end

otherwise your code in b.rb isn't aware of base.rb, and thus doesn't know about A::Base.

require 'base'

require 'lib/base' then

Thanks, this fixes it - but the actual path 'lib/base' is incorrect in the context of the file b.rb (b.rb is in the same directory as base.rb, therefore the line should be require 'base' no?)

--
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E 7C11 332A 551C 796C 9F04

11

"Christophe Grandsire" <christophe.grandsire@free.fr> wrote in message

Oops! Of course. "require"'s lookup system bit me again

I just added RCR-324.

    def require_relative(path)
      require File.join(File.dirname(caller[0]), path.to_str)
    end