Getting a method or class within a file

[Asfand Yar Qazi]

Hi,

I want to be able to do the following:

lots of Ruby files are in a directory, each containing stuff and a
method 'init_file'. I want to be able to 'require' each file, and
then call the 'init_file' method within that file.

Each file will have its own 'init_file' method, so I can't just do a:

require 'file'
init_file

because the init_file method will have been defined before hand.

Is it possible, like in Perl, for an included file to return a value?

 

[Pit Capitain]

I want to be able to do the following:

lots of Ruby files are in a directory, each containing stuff and a
method 'init_file'. I want to be able to 'require' each file, and then
call the 'init_file' method within that file.

Each file will have its own 'init_file' method, so I can't just do a:

require 'file'
init_file

because the init_file method will have been defined before hand.

Not that I would recommend that, but you can do

require 'file1'
init_file

require 'file2'
init_file

because the init_file method of file2 will overwrite the init_file method of file1.

But: of course this is bad style. Where do your Ruby files come from? Can't you
wrap the code in each file in a class or module?

Regards,
Pit

 

[Asfand Yar Qazi]

Not that I would recommend that, but you can do

require 'file1'
init_file

require 'file2'
init_file

because the init_file method of file2 will overwrite the init_file
method of file1.

But: of course this is bad style. Where do your Ruby files come from?
Can't you wrap the code in each file in a class or module?

It's also thread-unsafe.

You're right. I think what I'll do is to have a combination of a
Module name and a filename that will allow there to be an init method
contained within 'Module', contained within 'file'.

But then I'll have to store 2 entries: filename and module name. But
I suppose that's ok. Perhaps I should use the following syntax:

Module@path/to/file.rb

to show that a module is in a certain file?

 

[Austin Ziegler]

It's also thread-unsafe.

You're right. I think what I'll do is to have a combination of a
Module name and a filename that will allow there to be an init method
contained within 'Module', contained within 'file'.

But then I'll have to store 2 entries: filename and module name. But
I suppose that's ok. Perhaps I should use the following syntax:

Module@path/to/file.rb

to show that a module is in a certain file?

It sounds like you're basically doing a plugin framework.

Ruwiki uses something like this when reading its Token classes. Look
at lib/ruwiki/wiki/tokens.rb to see how I do it.

There is a plugin framework (FreeBASE) that may also be suitable for
you in this instance.

 

[Asfand Yar Qazi]

It sounds like you're basically doing a plugin framework.

I want to be able to load up objects 'on demand', i.e. when they're
needed and not before. In a very simple way, nothing fancy.

Ruwiki uses something like this when reading its Token classes. Look
at lib/ruwiki/wiki/tokens.rb to see how I do it.

There is a plugin framework (FreeBASE) that may also be suitable for
you in this instance.

Ah, thanks I'll take a look.

 

[Robert Klemme]

Hi,

I want to be able to do the following:

lots of Ruby files are in a directory, each containing stuff and a method
'init_file'. I want to be able to 'require' each file, and then call the
'init_file' method within that file.

Do you want to invoke init_file *always* if you require a file or just on
every first load? If it's the typical intialization stuff, here are three
methods you can use (see attached).

Each file will have its own 'init_file' method, so I can't just do a:

require 'file'
init_file

because the init_file method will have been defined before hand.

Is it possible, like in Perl, for an included file to return a value?

I think you can do that with load but not require because require returns
whether the file was read or not.

Kind regards

robert

 

[Asfand Yar Qazi]

Do you want to invoke init_file *always* if you require a file or just
on every first load? If it's the typical intialization stuff, here are
three methods you can use (see attached).

Not always, just the first time.

I think you can do that with load but not require because require
returns whether the file was read or not.

Actually, I just tested load, and it also just returns true. No
'value of last expression' returned.

Many thanks

 

[Joel VanderWerf]

Hi,

I want to be able to do the following:

lots of Ruby files are in a directory, each containing stuff and a
method 'init_file'. I want to be able to 'require' each file, and then
call the 'init_file' method within that file.

Each file will have its own 'init_file' method, so I can't just do a:

require 'file'
init_file

because the init_file method will have been defined before hand.

Is it possible, like in Perl, for an included file to return a value?

You can do this using the "script" lib I just mentioned on another thread.

---- main.rb ----
require 'script'

mod1 = Script.load("file1.rb")
mod2 = Script.load("file2.rb")

[mod1, mod2].each do |mod|
mod.init_file
puts "The value of X for #{mod.inspect} is #{mod::X}"
end

---- file1.rb ----
def init_file
puts "init for #{__FILE__}"
end

X = "One"

---- file2.rb ----
def init_file
puts "init for #{__FILE__}"
end

X = "Two"

------------------

Output:
init for /tmp/script-example/file1.rb
The value of X for #<Script:/tmp/script-example/file1.rb> is One
init for /tmp/script-example/file2.rb
The value of X for #<Script:/tmp/script-example/file2.rb> is Two


Script also defines #autoscript, which you can use like #autoload to
load the modules on demand and assign them to constants.

 

[ES]

I want to be able to load up objects 'on demand', i.e. when they're
needed and not before. In a very simple way, nothing fancy.

Kernel#autoload might be of use if you have a discrete set of files?

Ah, thanks I'll take a look.

E

 

[Asfand Yar Qazi]

Kernel#autoload might be of use if you have a discrete set of files?

Think loading up Actors in Areas of a Game - no discreteness here

 

[Asfand Yar Qazi]

Hi,

I want to be able to do the following:

lots of Ruby files are in a directory, each containing stuff and a
method 'init_file'. I want to be able to 'require' each file, and
then call the 'init_file' method within that file.

Each file will have its own 'init_file' method, so I can't just do a:

require 'file'
init_file

because the init_file method will have been defined before hand.

Is it possible, like in Perl, for an included file to return a value?

You can do this using the "script" lib I just mentioned on another thread.

---- main.rb ----
require 'script'

mod1 = Script.load("file1.rb")
mod2 = Script.load("file2.rb")

[mod1, mod2].each do |mod|
mod.init_file
puts "The value of X for #{mod.inspect} is #{mod::X}"
end

---- file1.rb ----
def init_file
puts "init for #{__FILE__}"
end

X = "One"

---- file2.rb ----
def init_file
puts "init for #{__FILE__}"
end

X = "Two"

------------------

Output:
init for /tmp/script-example/file1.rb
The value of X for #<Script:/tmp/script-example/file1.rb> is One
init for /tmp/script-example/file2.rb
The value of X for #<Script:/tmp/script-example/file2.rb> is Two


Script also defines #autoscript, which you can use like #autoload to
load the modules on demand and assign them to constants.

ahhh..........

this may be useful