For quite some time I have thought I shouldn’t parse my own command line arguments in Python, but each time I looked for the “right” way to do it, I turned back.<\/p>\n
Today, I decided to persist.<\/p>\n
Now I know why I turned back, the libraries were terrible.<\/p>\n
I want to have:<\/p>\n
mycleverprog.py mycommand --nifty-option\n<\/pre>\nWhere the command is to do one thing or do the opposite.\u00a0 It is a required thing to say which.<\/p>\n
The standard library argparse is a little obscure at first, but with a little reading it starts to make sense.\u00a0 Cool.<\/p>\n
Oh, dang!\u00a0 It is new in Python 2.7, and I am running 2.6.\u00a0 Okay, so let’s look at the deprecated optparse, it looks really similar, I’ll convert my embryonic code…<\/p>\n
Horrors!\u00a0 I don’t know the history of the project, but it looks like some “little minds” have been at work on this library.\u00a0 Because it is called “optparse” it doesn’t support “required options” because the term is self-contradictory.\u00a0 Come on!\u00a0 A very<\/em> common use case is to type a command with a required parameter following on the command line.\u00a0 Think Unix commands like “rm” or “mkdir” or “touch”, or …, you get the idea.\u00a0 These commands also have “options” that are optional.\u00a0 So someone built a library that handles the “options” but makes a point of not handling a required parameter, just because of an unfortunate name for the library!?!\u00a0 They even waste effort pontificating on why options should be optional?<\/p>\n
Bosch!<\/strong><\/p>\n
They do talk about “positional arguments” being required, but it isn’t clear whether they even support that.<\/p>\n
My solution?\u00a0 Download<\/p>\n
http:\/\/argparse.googlecode.com\/files\/argparse-1.2.1.tar.gz<\/pre>\nput argparse.py in<\/p>\n
\/usr\/local\/lib\/python2.6\/dist-packages<\/pre>\nand use argparse.\u00a0 My little utility will just be for personal use–at least for now. By the time I give it to anyone else, newer versions of Python will be standard.\u00a0 Or I can include a copy of argparse.py.<\/p>\n
-kb, the Kent who is slowly getting better and better at Python.<\/p>\n
\u00a92011 Kent Borg<\/p>\n","protected":false},"excerpt":{"rendered":"
For quite some time I have thought I shouldn’t parse my own command line arguments in Python, but each time I looked for the “right” way to do it, I turned back. Today, I decided to persist. Now I know why I turned back, the libraries were terrible. I want to have: mycleverprog.py mycommand –nifty-option […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[22,221,251],"class_list":["post-157","post","type-post","status-publish","format-standard","hentry","category-tech","tag-argparse","tag-optparse","tag-python"],"_links":{"self":[{"href":"https:\/\/www.borg.org\/index.php?rest_route=\/wp\/v2\/posts\/157","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.borg.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.borg.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.borg.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.borg.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=157"}],"version-history":[{"count":0,"href":"https:\/\/www.borg.org\/index.php?rest_route=\/wp\/v2\/posts\/157\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.borg.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=157"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.borg.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=157"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.borg.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=157"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}