Information about how to convert command line strings to Python objects. Action objects are used by an ArgumentParser to represent the information needed to parse a single argument from one or more strings from the command line. The keyword arguments to the Action constructor are also
| 739 | # ============== |
| 740 | |
| 741 | class Action(_AttributeHolder): |
| 742 | """Information about how to convert command line strings to Python objects. |
| 743 | |
| 744 | Action objects are used by an ArgumentParser to represent the information |
| 745 | needed to parse a single argument from one or more strings from the |
| 746 | command line. The keyword arguments to the Action constructor are also |
| 747 | all attributes of Action instances. |
| 748 | |
| 749 | Keyword Arguments: |
| 750 | |
| 751 | - option_strings -- A list of command-line option strings which |
| 752 | should be associated with this action. |
| 753 | |
| 754 | - dest -- The name of the attribute to hold the created object(s) |
| 755 | |
| 756 | - nargs -- The number of command-line arguments that should be |
| 757 | consumed. By default, one argument will be consumed and a single |
| 758 | value will be produced. Other values include: |
| 759 | - N (an integer) consumes N arguments (and produces a list) |
| 760 | - '?' consumes zero or one arguments |
| 761 | - '*' consumes zero or more arguments (and produces a list) |
| 762 | - '+' consumes one or more arguments (and produces a list) |
| 763 | Note that the difference between the default and nargs=1 is that |
| 764 | with the default, a single value will be produced, while with |
| 765 | nargs=1, a list containing a single value will be produced. |
| 766 | |
| 767 | - const -- The value to be produced if the option is specified and the |
| 768 | option uses an action that takes no values. |
| 769 | |
| 770 | - default -- The value to be produced if the option is not specified. |
| 771 | |
| 772 | - type -- The type which the command-line arguments should be converted |
| 773 | to, should be one of 'string', 'int', 'float', 'complex' or a |
| 774 | callable object that accepts a single string argument. If None, |
| 775 | 'string' is assumed. |
| 776 | |
| 777 | - choices -- A container of values that should be allowed. If not None, |
| 778 | after a command-line argument has been converted to the appropriate |
| 779 | type, an exception will be raised if it is not a member of this |
| 780 | collection. |
| 781 | |
| 782 | - required -- True if the action must always be specified at the |
| 783 | command line. This is only meaningful for optional command-line |
| 784 | arguments. |
| 785 | |
| 786 | - help -- The help string describing the argument. |
| 787 | |
| 788 | - metavar -- The name to be used for the option's argument with the |
| 789 | help string. If None, the 'dest' value will be used as the name. |
| 790 | """ |
| 791 | |
| 792 | def __init__(self, |
| 793 | option_strings, |
| 794 | dest, |
| 795 | nargs=None, |
| 796 | const=None, |
| 797 | default=None, |
| 798 | type=None, |
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