From: zuzu <sean.zuzu@...>
Date: 2004-10-02T05:38:41+09:00
Subject: Re: Ruby as a shell (was Re: irb: a great tool in it's own right)

do you just want pipes & filters but for ruby?
if so, look back on some of my old emails here w/ jim weirich about
dataflow and generators.
jim is my hero. :D

-z

On Sat, 2 Oct 2004 04:30:58 +0900, Eivind Eklund <eeklund@gmail.com> wrote:
> On Sat, 2 Oct 2004 00:09:59 +0900, Robert Klemme <bob.news@gmx.net> wrote:
> >
> > "Eivind Eklund" <eeklund@gmail.com> schrieb im Newsbeitrag
> > news:dc9b20bb041001065332408f65@mail.gmail.com...
> >
> > > On the subject (if not the Subject:): Have anybody played with make it
> > > possible to use Ruby for running sort-of shell scripts?
> >
> > This topic arises from time to time.  AFAIR there are IRB extensions that
> > make IRB shell-like.
> 
> I'm not thinking of IRB  - I'm thinking of scripting specifically.
> 
> > >  Ie, including
> > > pipes etc.
> >
> > IO.popen() uses pipes internally.  And I think there is also another
> > method.
> 
> Yes, but these are highly clumsy when doing complex operations.
> 
> > >  As it is, there are some programs that call a lot of shell
> > > commands that I write in sh instead of Ruby, and where I'd really like
> > > to do them in Ruby.
> >
> > Depending on what you do, you might notice that you don't need those shell
> > programs for the job.  For example, "cat" is easily done with File.open()
> > {|io|...} and "rm" can be taken care of by File.delete().
> 
> I know, but again: This does not handle the cases I'm interested in.
> 
> > > The starting point I see for something like this would be to override
> > > method_missing like above, but make it return an object where | is
> > > overridden, and that have handling of shell return codes.
> > >
> > > The challenges I see here is
> > > - It's not possible to override the trueness/falseness of an object,
> > > so we'd need to call a special method to find out if a command failed
> > > or passed
> > > - It is hard to implement -e (give an error if a complete shell line
> > > fails - but not if we have an fail || true).  Maybe trace_func could
> > > be of help here, though.
> >
> > I'm not sure whether I wanted Ruby scripts to look similar to shell
> > scripts or whether it's feasible to a degree that is satisfactory.
> 
> I don't want all Ruby programs to look like shell scripts.  However, I
> find the shell script syntax very convenient for some types of
> operations - more convenient than Ruby for programs where the chief
> operations are running external commands with pipes and filters.  I
> would like to be able to embed this into Ruby programs, and easily
> convert this kind of program from a shell script to Ruby for further
> massaging.
> 
> So yes, I really want an sh-like syntax inside my Ruby scripts - not
> for everything, but for the cases where I presently end up using sh
> because Ruby is inconvenient.
> 
> > I wouldn't mind having a method pipe(*commands) in Kernel or IO that starts
> > all these commands in parallel and connects them via pipes.
> 
> Intriguing idea.  I'd use an array per command instead of a string (to
> avoid white space parsing issues), but apart from that I like it :-)
> 
> It isn't quite what I'm thinking of, but it is more useful for the
> general case.  (I was thinking of something for very special cases,
> only usable inside particular blocks.)
> 
> Eivind.
> 
>