Ruby namespace question


#1

I require two ruby files which include two classes with the same name.
how can I specify which class I use?


#2

On Jan 20, 2009, at 17:11 , Zhao Yi wrote:

I require two ruby files which include two classes with the same name.
how can I specify which class I use?

class X; end # x.rb
class X; end # y.rb

same class, only one to specify. Files mean nothing in ruby, they’re
just vehicles for the parser.


#3

Ryan D. wrote:

On Jan 20, 2009, at 17:11 , Zhao Yi wrote:

I require two ruby files which include two classes with the same name.
how can I specify which class I use?

class X; end # x.rb
class X; end # y.rb

same class, only one to specify. Files mean nothing in ruby, they’re
just vehicles for the parser.

For this code:

require ‘x.rb’
require ‘y.rb’
X.new #which class it uses, can I specify the class like x.X or y.X?


#4

Zhao Yi wrote:

same class, only one to specify. Files mean nothing in ruby, they’re
just vehicles for the parser.

For this code:

require ‘x.rb’
require ‘y.rb’
X.new #which class it uses, can I specify the class like x.X or y.X?

Why not answer this empirically? Try it out!

t.

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#5

Tom C. wrote:

Why not answer this empirically? Try it out!

I have tried but failed. This is my code:

logger=log4r.Logger.new

and I got the error: undefined local variable or method log4r


#6

Zhao Yi wrote:

I think you want

logger = Log4r.Logger.new

or

logger = Log4r::Logger.new

But, glancing at the docs, you also need to specify a name for it, like

logger = Log4r::Logger.new “mylog”

Hope that helps.

-Justin


#7

yes,

logger = Log4r::Logger.new

works. thanks.


#8

Zhao Yi wrote:

Ryan D. wrote:

On Jan 20, 2009, at 17:11 , Zhao Yi wrote:

I require two ruby files which include two classes with the same name.
how can I specify which class I use?

class X; end # x.rb
class X; end # y.rb

same class, only one to specify. Files mean nothing in ruby, they’re
just vehicles for the parser.

For this code:

require ‘x.rb’
require ‘y.rb’
X.new #which class it uses, can I specify the class like x.X or y.X?

Nope - there is only one class X. Which file it was (first) defined in
makes no difference. If you require ‘x.rb’ first then class X is
created, and when you require ‘y.rb’ new methods are added into the
same class.

If you want them to be different, define them in different namespaces.
This is what Log4r:: does (it refers to the namespace, not the file)

module One; class X; end; end # x.rb
module Two; class X; end; end # y.rb

require ‘x’
require ‘y’
One::X.new # this is the one defined in x.rb
Two::X.new # this is the one defined in y.rb