OptionParser questions

I’m a bit confused by the way that OptionParser works. In
the “Complete example” on

http://www.ruby-doc.org/stdlib/libdoc/optparse/rdoc/classes/OptionParser.html

I see

opts = OptionParser.new do |opts|
opts.banner = “Usage: example.rb [options]”

It looks like the “opts” object is being handed to the block,
as well as being returned as the result of the “new” method.
Is this the case? Is this a common way of doing things? Are
there any caveats that must be observed in this situation?

-r

http://www.cfcl.com/rdm Rich M.
http://www.cfcl.com/rdm/resume [email protected]
http://www.cfcl.com/rdm/weblog +1 650-873-7841

Technical editing and writing, programming, and web development

Le 5 octobre 2006 à 21:03, Rich M. a écrit :

opts = OptionParser.new do |opts|
opts.banner = “Usage: example.rb [options]”

It looks like the “opts” object is being handed to the block,
as well as being returned as the result of the “new” method.
Is this the case?

Not really. I’d say that example is badly written. The
OptionParser.new call can take a block, with one parameter. The name
between || is the name of that parameter, and is a variable local to the
block. I’d write something like this myself :

opts = OptionParser.new do |o|
o.banner = …

end

(If the whole code is inside the block, you can even drop the first
assignment, too.)

Is this a common way of doing things? Are
there any caveats that must be observed in this situation?

I’m not good enough with the Ruby usages to reply here…

Fred

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