getopt – Command line option parsing(頁 1) - python - EcStart PHP 技術討論論壇 |PHP Technology Discussion Forum

FIEND 發表於 2009-2-26 13:41

getopt – Command line option parsing

<a href="http://docs.python.org/library/getopt.html" target="_blank">http://docs.python.org/library/getopt.html</a>

 <a href="http://www.doughellmann.com/PyMOTW/getopt/index.html" target="_blank">http://www.doughellmann.com/PyMOTW/getopt/index.html</a> <div class="section" id="module-getopt">
<h1>getopt – Command line option parsing<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#module-getopt" title="Permalink to this headline">¶</a></h1>
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<tr class="field"><th class="field-name">Purpose:</th><td class="field-body">Command line option parsing</td>
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<tr class="field"><th class="field-name">Python Version:</th><td class="field-body">1.4</td>
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The getopt module is the old-school command line option parser which supports
the conventions established by the Unix function getopt(). It parses an
argument sequence, such as sys.argv and returns a sequence of (option,
argument) pairs and a sequence of non-option arguments.
Supported option syntax includes:
<div class="highlight-python"><pre>-a -bval -b val --noarg --witharg=val --witharg val</pre>
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<div class="section" id="function-arguments">
<h2>Function Arguments<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#function-arguments" title="Permalink to this headline">¶</a></h2>
The getopt function takes three arguments:
<ul class="simple"><li>The first argument is the sequence of arguments to be parsed. This usually
comes from sys.argv[1:] (ignoring the program name in sys.arg[0]).</li><li>The second argument is the option definition string for single character
options. If one of the options requires an argument, its letter is followed
by a colon.</li><li>The third argument, if used, should be a sequence of the long-style option
names. Long style options can be more than a single character, such as
–noarg or –witharg. The option names in the sequence should not include
the – prefix. If any long option requires an argument, its name should have
a suffix of =.</li></ul>
Short and long form options can be combined in a single call.
</div>
<div class="section" id="short-form-options">
<h2>Short Form Options<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#short-form-options" title="Permalink to this headline">¶</a></h2>
If a program wants to take 2 options, -a, and -b with the b option requiring
an argument, the value should be “ab:”.
<div class="highlight-python"><div class="highlight"><pre>import getopt print getopt.getopt(['-a', '-bval', '-c', 'val'], 'ab:c:') </pre></div>
</div>
<div class="highlight-python"><pre>$ python getopt_short.py ([('-a', ''), ('-b', 'val'), ('-c', 'val')], [])</pre>
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</div>
<div class="section" id="long-form-options">
<h2>Long Form Options<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#long-form-options" title="Permalink to this headline">¶</a></h2>
If a program wants to take 2 options, –noarg and –witharg the sequence
should be [ ‘noarg’, ‘witharg=’ ].
<div class="highlight-python"><div class="highlight"><pre>import getopt print getopt.getopt([ '--noarg', '--witharg', 'val', '--witharg2=another' ], '', [ 'noarg', 'witharg=', 'witharg2=' ]) </pre></div>
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<div class="highlight-python"><pre>$ python getopt_long.py ([('--noarg', ''), ('--witharg', 'val'), ('--witharg2', 'another')], [])</pre>
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</div>
<div class="section" id="example">
<h2>Example<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#example" title="Permalink to this headline">¶</a></h2>
Below is a more complete example program which takes 5 options: -o, -v,
–output, –verbose, and –version. The -o, –output, and –version options
require an argument.
<div class="highlight-python"><div class="highlight"><pre>import getopt import sys version = '1.0' verbose = False output_filename = 'default.out' print 'ARGV :', sys.argv[1:] options, remainder = getopt.getopt(sys.argv[1:], 'o:v', ['output=', 'verbose', 'version=', ]) print 'OPTIONS :', options for opt, arg in options: if opt in ('-o', '--output'): output_filename = arg elif opt in ('-v', '--verbose'): verbose = True elif opt == '--version': version = arg print 'VERSION :', version print 'VERBOSE :', verbose print 'OUTPUT :', output_filename print 'REMAINING :', remainder </pre></div>
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The program can be called in a variety of ways.
<div class="highlight-python"><pre>$ python getopt_example.py ARGV : [] OPTIONS : [] VERSION : 1.0 VERBOSE : False OUTPUT : default.out REMAINING : []</pre>
</div>
A single letter option can be a separate from its argument:
<div class="highlight-python"><pre>$ python getopt_example.py -o foo ARGV : ['-o', 'foo'] OPTIONS : [('-o', 'foo')] VERSION : 1.0 VERBOSE : False OUTPUT : foo REMAINING : []</pre>
</div>
or combined:
<div class="highlight-python"><pre>$ python getopt_example.py -ofoo ARGV : ['-ofoo'] OPTIONS : [('-o', 'foo')] VERSION : 1.0 VERBOSE : False OUTPUT : foo REMAINING : []</pre>
</div>
A long form option can similarly be separate:
<div class="highlight-python"><pre>$ python getopt_example.py --output foo ARGV : ['--output', 'foo'] OPTIONS : [('--output', 'foo')] VERSION : 1.0 VERBOSE : False OUTPUT : foo REMAINING : []</pre>
</div>
or combined, with =:
<div class="highlight-python"><pre>$ python getopt_example.py --output=foo ARGV : ['--output=foo'] OPTIONS : [('--output', 'foo')] VERSION : 1.0 VERBOSE : False OUTPUT : foo REMAINING : []</pre>
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</div>
<div class="section" id="abbreviating-long-form-options">
<h2>Abbreviating Long Form Options<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#abbreviating-long-form-options" title="Permalink to this headline">¶</a></h2>
The long form option does not have to be spelled out entirely, so long as a
unique prefix is provided:
<div class="highlight-python"><pre>$ python getopt_example.py --o foo ARGV : ['--o', 'foo'] OPTIONS : [('--output', 'foo')] VERSION : 1.0 VERBOSE : False OUTPUT : foo REMAINING : []</pre>
</div>
If a unique prefix is not provided, an exception is raised.
<div class="highlight-python"><pre>$ python getopt_example.py --ver 2.0 ARGV : ['--ver', '2.0'] Traceback (most recent call last): File "getopt_example.py", line 44, in <module> 'version=', File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/getopt.py", line 89, in getopt opts, args = do_longs(opts, args[0][2:], longopts, args[1:]) File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/getopt.py", line 153, in do_longs has_arg, opt = long_has_args(opt, longopts) File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/getopt.py", line 180, in long_has_args raise GetoptError('option --%s not a unique prefix' % opt, opt) getopt.GetoptError: option --ver not a unique prefix</pre>
</div>
Option processing stops as soon as the first non-option argument is
encountered.
<div class="highlight-python"><pre>$ python getopt_example.py -v not_an_option --output foo ARGV : ['-v', 'not_an_option', '--output', 'foo'] OPTIONS : [('-v', '')] VERSION : 1.0 VERBOSE : True OUTPUT : default.out REMAINING : ['not_an_option', '--output', 'foo']</pre>
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</div>
<div class="section" id="gnu-style-option-parsing">
<h2>GNU-style Option Parsing<a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#gnu-style-option-parsing" title="Permalink to this headline">¶</a></h2>
New in Python 2.3, an additional function gnu_getopt() was added. It allows
option and non-option arguments to be mixed on the command line in any order.
<div class="highlight-python"><div class="highlight"><pre>import getopt import sys version = '1.0' verbose = False output_filename = 'default.out' print 'ARGV :', sys.argv[1:] options, remainder = getopt.gnu_getopt(sys.argv[1:], 'o:v', ['output=', 'verbose', 'version=', ]) print 'OPTIONS :', options for opt, arg in options: if opt in ('-o', '--output'): output_filename = arg elif opt in ('-v', '--verbose'): verbose = True elif opt == '--version': version = arg print 'VERSION :', version print 'VERBOSE :', verbose print 'OUTPUT :', output_filename print 'REMAINING :', remainder </pre></div>
</div>
After changing the call in the previous example, the difference becomes clear:
<div class="highlight-python"><pre>$ python getopt_gnu.py -v not_an_option --output foo ARGV : ['-v', 'not_an_option', '--output', 'foo'] OPTIONS : [('-v', ''), ('--output', 'foo')] VERSION : 1.0 VERBOSE : True OUTPUT : foo REMAINING : ['not_an_option']</pre>
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<div class="section" id="special-case">
<h2>Special Case: <tt class="docutils literal">--</tt><a class="headerlink" href="http://www.doughellmann.com/PyMOTW/getopt/index.html#special-case" title="Permalink to this headline">¶</a></h2>
If getopt encounters <tt class="docutils literal">--</tt> in the input arguments, it stops processing the remaining arguments as options.
<div class="highlight-python"><pre>$ python getopt_example.py -v -- --output foo ARGV : ['-v', '--', '--output', 'foo'] OPTIONS : [('-v', '')] VERSION : 1.0 VERBOSE : True OUTPUT : default.out REMAINING : ['--output', 'foo']</pre>
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<div class="admonition-see-also admonition seealso">
See also
<dl class="last docutils"><dt><a class="reference external" href="http://docs.python.org/library/getopt.html">getopt</a></dt><dd>The standard library documentation for this module.</dd><dt><a title="Command line option parser to replace getopt." class="reference external" href="http://www.doughellmann.com/PyMOTW/optparse/index.html#module-optparse"><tt class="xref docutils literal">optparse</tt></a></dt><dd>The <a title="Command line option parser to replace getopt." class="reference external" href="http://www.doughellmann.com/PyMOTW/optparse/index.html#module-optparse"><tt class="xref docutils literal">optparse</tt></a> module.</dd></dl>
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getopt – Command line option parsing