Feature #6648

Provide a standard API for retrieving all command-line flags passed to Ruby

Added by Charles Nutter almost 2 years ago. Updated over 1 year ago.

[ruby-core:45867]
Status:Assigned
Priority:Normal
Assignee:Yukihiro Matsumoto
Category:-
Target version:next minor

Description

=begin
Currently there are no standard mechanisms to get the flags passed to the currently running Ruby implementation. The available mechanisms are not ideal:

  • Scanning globals and hoping they have not been tweaked to new settings
  • Using external wrappers to launch Ruby
  • ???

Inability to get the full set of command-line flags, including flags passed to the VM itself (and probably VM-specific) makes it impossible to launch subprocess Ruby instances with the same settings.

A real world example of this is "((%bundle exec%))" when called with a command line that sets various flags, a la ((%jruby -Xsome.vm.setting --1.9 -S bundle exec%)). None of these flags can propagate to the subprocess, so odd behaviors result. The only option is to put the flags into an env var (((|JRUBY_OPTS|)) or ((|RUBYOPT|))) but this breaks the flow of calling a simple command line.

JRuby provides mechanisms to get all its command line options, but they require calling Java APIs from Ruby's API set. Rubinius provides its own API for accessing comand-line options, but I do not know if it includes VM-level flags as well as standard Ruby flags.

I know there is a (({RubyVM})) namespace in the 2.0 line. If that namespace is intended to be general-purpose for VM-level features, it would be a good host for this API. Something like...

class << RubyVM
def vm_args; end # returns array of command line args not passed to the target script

def script; end # returns the script being executed...though this overlaps with $0

def script_args; end # returns args passed to the script...though this overlaps with ARGV, but that is perhaps warranted since ARGV can be modified (i.e. you probably want the original args)

end
=end


Related issues

Duplicates ruby-trunk - Feature #4046: Saving C's **argv and cwd allows Ruby programs to reliabl... Feedback 11/12/2010

History

#1 Updated by Charles Nutter almost 2 years ago

Oops, this should be a feature request.

#2 Updated by Nobuyoshi Nakada almost 2 years ago

  • Tracker changed from Bug to Feature

I'm positive to the feature, but RubyVM wouldn't be right place.
It is CRuby specific and unexpected to be in other implementations.

#3 Updated by Nobuyoshi Nakada almost 2 years ago

  • Description updated (diff)

#4 Updated by Charles Nutter over 1 year ago

ARGV is a special class; perhaps ARGV could have the methods?

#5 Updated by Charles Nutter over 1 year ago

I was mistaken...it is ARGF, not ARGV that is a special class. ARGV is a normal array.

Another option: ENV, which is a special Hash-like class. ENV.vmargs, ENV.script, and ENV.scriptargs aren't bad.

#6 Updated by Charles Nutter over 1 year ago

Ping...we'd still like to have this to be able to build a unifying benchmark tool, which needs to be able to report the actual command-line arguments passed to the runtime. Current tricks are too ugly (parsing ps output, for example), and this would not be difficult to add.

I'm leaning toward ENV having a few special methods for this, but I'm open to other ideas.

#7 Updated by Yusuke Endoh over 1 year ago

  • Status changed from Open to Assigned
  • Assignee set to Yukihiro Matsumoto
  • Target version set to next minor

I'm sorry that matz didn't noticed this.

Yusuke Endoh mame@tsg.ne.jp

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