Dynamically load methods from external source


#1

I know this sounds like it could be a very bad thing to do, but I was
wondering if there is a way to load methods into an already running app
from an external source (database/file). I am building an app that
would load needed code snippets for a given task, but each time it runs
it will not need all the snippets, just certain ones. I know that I can
store the code as text in the database/file, but will I have to execute
it externally (via system ‘ruby file.rb arg1 arg2’), or can I load and
execute it internally (possibly in a separate thread)? I can think of
all sorts of reasons why to NOT do this, but still, there is curiosity
isn’t there…

I am thinking that somehow Rails does something like this with it’s
controllers, but heck, that is a lot of code to sort through.


#2

I have a long running ruby process which does just this. There’s a drb
port open on the process. If a method is changed, I open an irb
session, connect to drb, and run “load” on the remote process to reload
the file containing the changed methods. To reduce the typing I have
an rload method in the object exposed by drb.


#3

On 1/10/07, Daniel S. removed_email_address@domain.invalid wrote:

I am thinking that somehow Rails does something like this with it’s
controllers, but heck, that is a lot of code to sort through.

use Kernel#eval for loading* code from string,
load/require to load code from file.
(require will load just once, load will more times)

loading = load and execute