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Python中的getopt函数使用详解

作者:低调小一

这篇文章主要介绍了Python中的getopt函数使用详解,是Python进阶学习中的重要知识,需要的朋友可以参考下

函数原型:

getopt.getopt(args, shortopts, longopts=[])


参数解释:

返回值:

源码分析

在Android生成OTA的build系统中,common.py文件中的ParseOptions函数就是用来解析输入参数的,我们来通过该函数的实现来分析一下getopt的使用。

函数源码如下:

def ParseOptions(argv, docstring, extra_opts="", extra_long_opts=(), extra_option_handler=None):
 try:
 opts, args = getopt.getopt(
  argv, "hvp:s:x" + extra_opts,
  ["help", "verbose", "path=", "signapk_path=", "extra_signapk_args=", "java_path=", "public_key_suffix=", "private_key_suffix=", "device_specific=", "extra="] + list(extra_long_opts))
 except getopt.GetoptError, err:
 Usage(docstring)
 print "**", str(err), "**"
 sys.exit(2)

 path_specified = False

 for o, a in opts:
 if o in ("-h", "--help"):
  Usage(docstring)
  sys.exit()
 elif o in ("-v", "--verbose"):
  OPTIONS.verbose = True
 elif o in ("-p", "--path"):
  OPTIONS.search_path = a
 elif o in ("--signapk_path",):
  OPTIONS.signapk_path = a
 elif o in ("--extra_singapk_args",):
  OPTIONS.extra_signapk_args = shlex.split(a)
 elif o in ("--java_path",):
  OPTIONS.java_path = a
 else:
  if extra_option_handler is None or not extra_option_handler(o, a):
  assert False, "unknown option \"%s\"" % (o,)

 os.environ["PATH"] = (os.path.join(OPTIONS.search_path, "bin") + os.pathsep + os.environ["PATH"])

 return args

其中,extra_option_handler可以理解为函数指针,它的功能也是解析opts的键值对。
extra_option_handler源码如下:

 

def option_handler(o, a):
 if o in ("-b", "--board_config"):
 pass # deprecated
 elif o in ("-k", "--package_key"):
 OPTIONS.package_key = a
 elif o in ("-i", "--incremental_from"):
 OPTIONS.incremental_source = a
 elif o in ("-w", "--wipe_user_data"):
 OPTIONS.wipe_user_data = True
 elif o in ("-n", "--no_prereq"):
 OPTIONS.omit_prereq = True
 elif o in ("-e", "--extra_script"):
 OPTIONS.extra_script = a
 elif o in ("-a", "--aslr_mode"):
 if a in ("on", "On", "true", "True", "yes", "Yes"):
 OPTIONS.aslr_mode = True
 else:
 OPTIONS.aslr_mode = False
 elif o in ("--worker_threads"):
 OPTIONS.worker_threads = int(a)
 else:
 return False
 return True


一般生成OAT全量包的参数argv如下:

复制代码 代码如下:
argv = ['-v', '-p', 'out/host/linux-xxx', '-k', 'build/target/product/security/testkey', 'out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip', 'out/target/product/xxx/xxx_20150723.1340-ota.zip']


首先,对参数进行分析,其中短参数包括:
-v,-p,-k,


经过解析后,生成的结果如下所示:

复制代码 代码如下:
opts = [('-v', ''), ('-p', 'out/host/linux-x86'), ('-k', 'build/target/product/security/testkey')]
args =['out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip', 'out/target/product/xxx/xxx_20150723.1340-ota.zip']

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