From: dilinger <dilinger@...>
Date: 2005-01-13T05:36:16+09:00
Subject: Re: return code from Open3.popen?

Yes, there are certainly plenty out there.

Really, there needs to be a consistent interface for this sort of
thing; there are plenty of functions out there that execute commands
(IO.popen, Kernel.system, Open3.popen3, etc) that all do slightly
different things wrt $?, depending upon their implementation.  That
should be hidden from the user; it should also be possible to define
your own method to run commands in ruby, and override $? (it is
currently read-only from within ruby).  Personally, I'd rather see an
exception thrown if the command fails, perhaps w/ an additional
argument to specify that you don't care if the command fails.  How that
should happen within IO.popen()'s block is interesting, though.  As it
stands, $? is not set until the block exits.  So:

IO.popen('nonexistantcommand') { |f|
puts $?.exitstatus
}
puts $?.exitstatus

The first will return the last command run *before* the popen.  If the
command exits immediately (ie, because the command doesn't exist),
should an exception be thrown as soon as it is realized that the
command failed?  Or, should the block be executed regardless of whether
the command failed or not, and an exception thrown after the block as
completed?