From: Mathieu Bouchard <matju@...>
Date: 2001-01-12T14:59:29+09:00
Subject: [ruby-talk:9182] Re: "|" on front of aPortName

> Same for the "|-" variant that spawns another Ruby
> interpreter... how/why/when would you use this?

The "|-" is mostly like popen(). One reason to use it is to be able to use
OS-level sandboxing, like limiting a process size, chroot(), jail(),
setuid(), etc. For untrusted code (unstable or malicious).

Apart from that you can use it if you want to avoid Ruby's threading
mechanism. For instance, Ruby's model is preemptive at the Ruby level, but
cooperative at the C level (?). If you want to support several CPU's you 
have to fork. If you want to access C libraries that block, you have to
fork. If you want the simplicity of having each object in exactly one
thread, you fork.

(That's my understanding of it.)

matju