I'd like to get the exact option flag that was specified on the command line from within Ruby's OptionParser.
For example, suppose I have the following code:
parser = OptionParser.new {
|opts|
opts.on('-f', '--file FILE', 'filename') {
|arg|
$filename = arg
# Here I'd like to know whether '-f' or '--file' was entered
# on the command line.
}
# ... etc. ...
}
I'd like to know whether the user happened to type '-f' or '--file' on the command line. Is this possible without writing two separate opts.on blocks?
I don't think you can get the flags being passed in when inside the OptionParser.new block. At that point it's too late. However, prior to OptionParser parsing the command-line, it's possible to look and see what's being passed in.
ARGV contains the raw command-line. For instance, if this is the command-line invocation for some code:
foo -i 1 -j 2
then ARGV will contain:
["-i", "1", "-j", "2"]
and, then it becomes pretty easy to grab the flags:
ARGV.grep(/^-/) # => ["-i", "-j"]
There are other OptionParser-like tools for Ruby, and those might let you access the flags being used, but I can't think of a reason I'd ever care to. Looking at your code it seems like you're not understanding how to use OptionParser:
parser = OptionParser.new {
|opts|
opts.on('-f', '--file FILE', 'filename') {
|arg|
$filename = arg
# Here I'd like to know whether '-f' or '--file' was entered
# on the command line.
}
# ... etc. ...
}
Instead of doing it that way, I'd write it:
options = {}
OptionParser.new do |opts|
opts.on('-f', '--file FILE', 'filename') { |arg| options[:filename] = arg }
end.parse!
if options[:filename]
puts 'exists' if File.exist?(options[:filename])
end
Then, later in your code you can check in the options hash to see if either of the -f or --file options was given, and what the value was. That it was one or the other of -f or --file shouldn't ever matter.
If it does then you need to differentiate between the two flags, instead of treating them as if they're aliases:
options = {}
OptionParser.new do |opts|
opts.on('-f', 'filename') { |arg| options[:f] = arg }
opts.on('--file FILE', 'filename') { |arg| options[:file] = arg }
end.parse!
if options[:file] || options[:f]
puts 'exists' if File.exist?(options[:file] || options[:f])
end