I'm trying to pick up ruby by porting a medium-sized (non-OO) perl program. One of my personal idioms is to set options like this:
use Getopt::Std;
our $opt_v; # be verbose
getopts('v');
# and later ...
$opt_v && print "something interesting\n";
In perl, I kind of grit my teeth and let $opt_v be (effectively) a global.
In ruby,the more-or-less exact equivalent would be
require 'optparse'
opts.on("-v", "--[no-]verbose", TrueClass, "Run verbosely") {
|$opt_verbose|
}
opts.parse!
end
where $opt_verbose is a global that classes could access. Having classes know about global flags like that seems ... er ... wrong. What's the OO-idiomatic way of doing this?
updated: Thanks for the answers suggesting optparse, but I should have been clearer that it's not how to process command-line options I'm asking about, but more the relationship between command-line options that effectively set a global program state and classes that should ideally be independent of that sort of thing.
A while back I ran across this blog post (by Todd Werth) which presented a rather lengthy skeleton for command-line scripts in Ruby. His skeleton uses a hybrid approach in which the application code is encapsulated in an application class which is instantiated, then executed by calling a "run" method on the application object. This allowed the options to be stored in a class-wide instance variable so that all methods in the application object can access them without exposing them to any other objects that might be used in the script.
I would lean toward using this technique, where the options are contained in one object and use either attr_writers or option parameters on method calls to pass relevant options to any additional objects. This way, any code contained in external classes can be isolated from the options themselves -- no need to worry about the naming of the variables in the main routine from within the thingy
class if your options are set with a thingy.verbose=true
attr_writer or thingy.process(true)
call.
The optparse library is part of the standard distribution, so you'll be able to use it without requiring any third party stuff.
I haven't used it personally, but rails seems to use it extensively and so does rspec , which I guess is a pretty solid vote of confidence
This example from rails' script/console
seems to show how to use it pretty easily and nicely
关于“ 处理红宝石中的命令行选项 ”谷歌的第一个热门话题是一篇关于Trollop的文章,它似乎是这项工作的好工具。
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