Functions to parse and access the arguments given to the program on the command line : Command Line « Utility « Python

1. Python
2. Utility
3. Command Line

Functions to parse and access the arguments given to the program on the command line

"""Handle command line arguments.

This module contains functions to parse and access the arguments given
to the program on the command line.
"""

import types
import string
import sys

# Symbolic constants for the indexes into an argument specifier tuple.
NAME        = 0
MANDATORY   = 1
TYPE        = 2
HELP        = 3
DEFAULT     = 4
SPEC_LENGTH = 5

Bool = []

helpSpec = (
  ('help',            0, Bool,   'print help and exit'),
)

def parseArgs(title, argv, argSpecs, filesOK):
  """Parse and check command line arguments.

  Scan the command line arguments in *argv* according to the argument
  specifier *argSpecs*. Return **None** if there are no errors in
  the arguments, otherwise return an error string describing the error.

  This function must be called to initialise this module.

  title    -- The name of the program. This is used when returning
              error messages or help text.

  argv     -- A sequence containing the arguments given to the program.
              Normally **sys.argv**.

  argSpecs -- A sequence of argument specifiers.  Each specifier describes
              a valid command line argument and consists of 4 or 5 items:

        - The argument name (without a leading minus sign **-**).

        - A boolean value, true if the argument is mandatory.

        - This should be **Args.Bool** if the argument has no option.
    Otherwise it should be a string describing the option
    required for this argument. This is used when printing help.

        - A short string describing the argument.

        - The default value of the argument.  This should only be used
          for non-mandatory arguments expecting an option.
        
        For example:
    (
      ('foreground', 0, 'colour',    'colour of text', 'black'),
      ('geometry',   0, 'spec',      'geometry of initial window'),
      ('server',     1, 'ompserver', 'ompserver to connect to'),
      ('silent',     0, Args.Bool,   'do not sound bell'),
    )
  """

  global programName
  global _fileList

  errMsg = title + ' command line error: '
  programName = argv[0];

  argSpecs = helpSpec + argSpecs
  argSpecDic = {}
  for spec in argSpecs:
    arg = spec[NAME]
    argSpecDic[arg] = spec
    if len(spec) >= SPEC_LENGTH:
      set(arg, spec[DEFAULT])
    elif spec[TYPE] is Bool:
      set(arg, 0)
    else:
      set(arg, None)

  knownKeys = argSpecDic.keys()

  i = 1
  _fileList = []
  argc = len(argv)
  while i < argc:
    arg = argv[i]
    key = arg[1:]
    if key in knownKeys:
      spec = argSpecDic[key]
      if spec[TYPE] is Bool:
  set(key, 1)
      else:
  i = i + 1
  if i >= argc:
    return errMsg + 'missing argument to \'' + arg + '\' option.'
  value = argv[i]
  if len(spec) >= SPEC_LENGTH:
    try:
        if type(spec[DEFAULT]) == types.IntType:
      typeStr = 'integer'
      value = string.atoi(value)
        elif type(spec[DEFAULT]) == types.FloatType:
      typeStr = 'float'
      value = string.atof(value)
    except:
        sys.exc_traceback = None   # Clean up object references
        return errMsg + 'cannot convert string \'' + value + \
          '\' to ' + typeStr + ' for option \'-' + key + '\'.'
  set(key, value)
    else:
      _fileList.append(arg)
    i = i + 1

  if get('help'):
    return _helpString(title, argSpecs)

  if not filesOK and len(_fileList) > 0:
    if len(_fileList) == 1:
      return errMsg + 'unknown option \'' + str(_fileList[0]) + '\'.'
    else:
      return errMsg + 'unknown options ' + str(_fileList) + '.'


  _missing = []
  for spec in argSpecs:
    if spec[MANDATORY] and get(spec[NAME]) is None:
      _missing.append(spec[NAME])
  if len(_missing) == 1:
    return errMsg + 'required argument \'-' + \
      str(_missing[0]) + '\' is missing.'
  elif len(_missing) > 1:
    return errMsg + 'required arguments ' + \
      str(map(lambda s: '-' + s, _missing)) + ' are missing.'

  return None

def fileList():
  return _fileList

def _helpString(title, argSpecs):
  max = 0
  for spec in argSpecs:
    if spec[TYPE] is Bool:
      width = len(spec[NAME]) + 1
    else:
      width = len(spec[NAME]) + 4 + len(spec[TYPE])
    if width > max:
      max = width

  rtn = title + ' command line arguments:'
  format = '\n  %-' + str(max) + 's %s'
  for mandatory in (1, 0):
    needHeader = 1
    for spec in argSpecs:
      if mandatory and spec[MANDATORY] or not mandatory and not spec[MANDATORY]:
  if needHeader:
    if mandatory:
      rtn = rtn + '\n Mandatory arguments:'
    else:
      rtn = rtn + '\n Optional arguments (defaults in parentheses):'
    needHeader = 0
  if spec[TYPE] is Bool:
    arg = '-%s' % spec[NAME]
  else:
    arg = '-%s <%s>' % (spec[NAME], spec[TYPE])
  if len(spec) >= SPEC_LENGTH:
    if type(spec[DEFAULT]) == types.StringType:
        definition = spec[HELP] + ' (' + spec[DEFAULT] + ')'
    else:
        definition = spec[HELP] + ' (' + str(spec[DEFAULT]) + ')'
  else:
    definition = spec[HELP]
  rtn = rtn + format % (arg, definition)

  return rtn

def exists(key):
    return configDict.has_key(key)

def get(key):
    return configDict[key]

def set(key, value):
    global configDict

    configDict[key] = value

configDict = {}

           
       

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