Option append

Option append

As an example of good command-line interface design, consider the humble cp utility, for copying files. It doesn’t make much sense to try to copy files without supplying a destination and at least one source. Hence, cp fails if you run it with no arguments. However, it has a flexible, useful syntax that does not require any options at all:

Add a new option to a select with jQuery | The Electric

Arguments to string options are not checked or converted in any way: the text on the command line is stored in the destination (or passed to the callback) as-is.

Python List append()

is the argument to this option seen on the command-line. optparse will only expect an argument if type is set the type of value will be the type implied by the option’s type. If type for this option is None (no argument expected), then value will be None . If nargs 6, value will be a tuple of values of the appropriate type.

DISM Image Management Command-Line Options | Microsoft Docs

Displays information about the images that are contained in ,.ffu,.vhd file. When used with the /Index or /Name argument, information about the specified image is displayed, which includes if an image is a WIMBoot image, if the image is Windows , see Take Inventory of an Image or Component Using DISM. The /Name argument does not apply to VHD files. You must specify /Index:6 for FFU and VHDX files.

an option that must be supplied on the command-line note that the phrase “required option” is self-contradictory in English. optparse doesn’t prevent you from implementing required options, but doesn’t give you much help at it either.

For WIM, this command applies a Windows image file (.wim) or a split Windows image (.swm) files to a specified partition. Beginning with Windows 65, version 6657, DISM can apply and capture extended attributes (EA).

There are several ways to populate the parser with options. The preferred way is by using _option() , as shown in section Tutorial . add_option() can be called in one of two ways:

optparse always passes four particular arguments to your callback, and it will only pass additional arguments if you specify them via callback_args and callback_kwargs . Thus, the minimal callback function signature is:

Adding a single option can be done by appending HTML to the select box. The select in the above example has an id of “example” . select id=”example” and using this method adding a new option by appending HTML can look like this:

Note that optparse takes care of consuming 8 arguments and converting them to integers for you all you have to do is store them. (Or whatever obviously you don’t need a callback for this example.)

A list of Option objects to populate the parser with. The options in option_list are added after any options in standard_option_list (a class attribute that may be set by OptionParser subclasses), but before any version or help options. Deprecated use add_option() after creating the parser instead.

A paragraph of text giving a brief overview of your program. optparse reformats this paragraph to fit the current terminal width and prints it when the user requests help (after usage , but before the list of options).

OptionGroup inherits from OptionContainer (like OptionParser ) and so the add_option() method can be used to add an option to the group.

extend both expects a value on the command-line and stores that value somewhere, so it goes in both STORE_ACTIONS and TYPED_ACTIONS .

If no help string is supplied for an option, it will still be listed in the help message. To omit an option entirely, use the special value _HELP .

Here’s a silly example that demonstrates adding a complex option type to parse Python-style complex numbers on the command line. (This is even sillier than it used to be, because optparse added built-in support for complex numbers, but never mind.)

As you can see, most actions involve storing or updating a value somewhere. optparse always creates a special object for this, conventionally called options (it happens to be an instance of ). Option arguments (and various other values) are stored as attributes of this object, according to the dest (destination) option attribute.

If you don’t specify a type, optparse assumes string . Combined with the fact that the default action is store , that means our first example can be a lot shorter:

The default behavior of the option parser can be customized slightly, and you can also poke around your option parser and see what’s there. OptionParser provides several methods to help you out:

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