Code organisation "template" interference(?) with RUBYLIB en

casper_the_ghost · March 10, 2007, 12:25am

(Warning: this post is waaaaay longer than I intended)

Hello,

Apologies if the subject line is a bit cryptic, but it’s not easy to
describe in a single
line. Anyway…

A while back an astute fellow on comp.lang.ruby (thanks RobertK!)
provided me with some
advice on how to lay out ruby classes and code that ended up being so
useful that I’ve
applied the same organisational template for several projects. I may
have butchered the
advice, but basically I have the following sort of setup (apologies for
the lengthy ASCII
art too),

etc.

For any project, call it module ProjectX:

the lib/projectX.rb file (class Project2::Runner) is the interface to
a
user. It’s the “main” runner class if you like.
the ProjectX::Config class holds, surprise, all the configuration info
(usually read in from a text file)
the ProjectX::Base clase holds all the constants and methods that are
shared throughout any particular ProjectX module
the ProjectX::RunnerY::Base class holds all the constants and methods
that are shared throughout any particular ProjectX::RunnerY module
the ProjectX::RunnerY::Runner class is the controller that iterates
over
all the current module classes (the Class1, Class2,…ClassZ etc) and
invokes their methods
the ProjectX::RunnerY::ClassZ class actually does something. :o)

I like the above setup because it scales quite well. For some projects
each “runnerY”
contains another layer. It’s made it really easy to isolate
functionality and test it.

Anyway, the problem I’m having now is I decided to consolidate all my
code on a single
machine and tack on the various locations of everything onto the RUBYLIB
envar, i.e.

export RUBYLIB=$HOME/ruby/project1/lib:$HOME/ruby/project2/lib: etc…

So now when I do something like the following in
project2/lib/runner1/base.rb,

require ‘base/base’
module Proj2
module Runner1
class Base < Proj2::Base
# This is how the config gets passed along in
# Runner1 module and holds shared Runner1 code
end
end
end

and in project2/lib/runner1/runner.rb,

require ‘runner1/base’
module Proj2
module Runner1
class Runner < Proj2::Runner1::Base
RUNNERS=[Class1,Class2,…,ClassZ]
def run
RUNNERS.each do |run_class|
r = run_class.new
r.config = self.config
r.run
end
end
end
end
end

and invoke the main script, ruby searches the RUBYLIB paths and finds
the “base/base.rb”
for project1 first (since it’s listed first) and loads that file
instead of the
“base/base.rb” for project2. Thus, I get errors like:

project2/lib/runner1/base.rb:4: uninitialized constant Project2::Base
(NameError)

If I swap the listing in my RUBYLIB envar so that the project2 directory
is listed first,
everything is honky dory and runs fine.

Phewph! If you’ve made it this far, the beer is on me if we ever meet.

My questions are:

can I keep my current directory structure (which, believe it or not,
seems quite
logical to me) and avoid these file loading order problems?
IF not, how to fix this? I like the idea of generic file names and
classes (config,
base) across projects so that those that follow can grok multiple
projects after studying
the docs for just one.

Thanks for any insight.

cheers,

paulv

casper_the_ghost · March 10, 2007, 3:49pm

On Sat, Mar 10, 2007 at 08:25:09AM +0900, Paul van Delst wrote:

—project1 (module Proj1)
| |–lib
| | |—project1.rb (class Proj1::Runner)
| | |—config
| | | |
| | | `–config.rb (class Proj1::Config)
…
require ‘base/base’
module Proj2
module Runner1

I’d suggest putting a single entry in your load path, for the very top
level
of your directory structure, and then use

require ‘project1/lib/base/base’

instead of

require ‘base/base’

This is the simplest way of easily distinguishing project1 from project2
if
the subdirectories and files contained by both have the same names
(especially if project1 needs to use files within project2)

If all projects are independent, then clearly when you run an
application
from project1 you only need to put project1’s lib directory into the
RUBYLIB
environment.

If you want to automate this, then create a bunch of files at the top
level
of your lib tree

[project1.rb]
$:.unshift “/path/to/project1/lib”

[project2.rb]
$:.unshift “/path/to/project2/lib”

Then your programs can say:

require ‘project1’
require ‘base/base’

or whatever. (That means you only need to put one extra line at the top
of
each source file)

Just a couple of ideas.

B.

casper_the_ghost · March 12, 2007, 3:25pm

Brian C. wrote:

module Runner1
This is the simplest way of easily distinguishing project1 from project2 if
the subdirectories and files contained by both have the same names
(especially if project1 needs to use files within project2)

Hi Brian,

Your suggestion is how I first thought about “fixing” my problem. But
when other folks
check out my code from the repository, they may not have the same
directory structure as I
do. Then I get calls about files not found etc.

[project2.rb]
$:.unshift “/path/to/project2/lib”

Then your programs can say:

require ‘project1’
require ‘base/base’

or whatever. (That means you only need to put one extra line at the top of
each source file)

Thanks for the tip. I think I’ll look into this… I do something like
this for my test cases.

cheers,

paulv

casper_the_ghost · March 12, 2007, 3:51pm

Brian C. wrote:

require ‘project1’
require ‘base/base’

or whatever. (That means you only need to put one extra line at the top of
each source file)

Hi again,

I just tried adding

$:.unshift File.join(File.dirname(FILE))

to the “parent” file and it works a treat!

I should’ve figured it out on my own, but thanks muchly for the
hint/nudge-in-right-direction. :o)

cheers,

paulv