Options

Adding to the hello world example from the intro, the displayed text could be made configurable with an option:

vd.option('disp_hello', 'Hello world!', 'string to display for hello-world command')

BaseSheet.addCommand('1', 'hello-world', 'status(options.disp_hello)')

Now the user can set the option to modify which text is displayed during their session when they press 1. For example, on the command line (note that the underscores can be converted to hyphens):

vd --disp-hello="¡Hola mundo!"

The user can override it persistently for every session by adding a line to their .visidatarc:

options.disp_hello = 'Bonjour monde!'

Options Context

Options can have different values depending on the context in which they’re used. For instance, one TSV sheet might need its delimiter set to “|”, while another TSV sheet in the same session might need to use the default (”\t”, or TAB) instead.

Options can be overridden globally, or for all sheets of a specific type, or only for one specific sheet.

The options context should be referenced directly when setting:

  • sheet.options to set an option on a specific sheet instance (sheet override).

  • <SheetType>.class_options to set a option default for a particular type of Sheet (class override).

  • vd.options (or plain options) to set an option globally for all sheets, except for sheets that have a sheet override (global override).

Use sheet.options to get an option within the context of a specific sheet. This is strongly preferred, so the user can override the option setting on a sheet-specific basis. However, some options and situations are truly sheet-agnostic, and so vd.options (or plain options) will get an option using the context of the top sheet.

When getting an option value, VisiData will look for a sheet override first, then class overrides next (from most specific subclass all the way up to BaseSheet), then a global override, before returning the default value from the option definition itself.

In general, plugins should use FooSheet.class_options to override values for the plugin-specific sheet type.

Note

Because it allows so much flexibility, getting option values is a comparatively slow operation. For tight loops, save the option into a local variable in an outer block. An option value can only change between commands anyway.

Options API

visidata.vd.options.__getattr__(optname)

Return value of option optname for stored options context.

x = sheet.options.hello_world is the preferred style for getting a single option value.

visidata.vd.options.__setattr__(optname, value)

Set value of option optname for stored options context.

sheet.options.hello_world = "Привет мир" is the preferred style for setting a single option value.

visidata.vd.options.get(optname, default=None)

Return the value of the given optname option in the options context. default is only returned if the option is not defined. An Exception is never raised.

visidata.vd.options.set(optname, value, obj='global')

Override value for optname in the options context, or in the obj context if given.

visidata.vd.options.unset(optname, obj=None)

Remove setting value for given context.

New in version 2.1.

visidata.vd.options.getall(prefix='')

Return dictionary of all options beginning with prefix (with prefix removed from the name).

The dict returned by options.getall('foo_') is designed to be used as kwargs to other loaders, so that their options can be passed through VisiData transparently. For example, to pass all csv options through to the builtin Python csv module:

csv.reader(fp, **sheet.options.getall('csv_'))
visidata.vd.option(name, default, helpstr, replay=False, sheettype=<class 'visidata.basesheet.BaseSheet'>)

Declare a new option.

  • name: name of option

  • default: default value when no other override exists

  • helpstr: short description of option (as shown in the Options Sheet)

  • replay: True if changes to the option should be stored in the Command Log

  • sheettype: None if the option is not sheet-specific, to make it global on CLI

Note

If the option affects loading, transforming, or saving, then set replay to True.

Rules for naming options

  • Options defined within a plugin should all start with the same short module abbreviation, like “mod_”.

  • Except for theme option names, which should start with “disp_” for a displayed string and “color_” for a color option (see Colors).

  • Use common abbreviations instead of full words.

  • Use “_” (underscore) to separate words.

  • Keep the option name length under 20 characters. Maximum of 3 words (2 separators).

Note

  • Consider whether some subset of options can be passed straight through to the underlying Python library via kwargs (maximum power with minimal effort).

Option type

When setting an option, strings and other types will be coerced to the type of the default. An Exception is raised if conversion fails. A default of None allows any type.

Examples

vd.option('disp_hello', 'Hello world!', 'string to display for hello-world')

# option without regard to a current sheet (global override only)
vd.options.disp_hello = 'こんにちは世界'

# show the option value given the context of a specific sheet
vd.status(sheet.options.disp_hello)

# option set on specific sheet only
sheet.options.color_current_row = 'bold blue'

# option set for all DirSheets
DirSheet.class_options.color_current_row = 'reverse green'