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Simple CLI Menus

Project description

Use python? Use the CLI? Ever prompt a user to select an option? I have just the module for you!

pimento is a simple CLI menu module for python. It also comes with a standalone command-line executable of the same name.

examples

simple CLI menu prompting

There is a single required argument:

  • items - a finite iterable (list, tuple, etc) of items which the user will be prompted to choose from
from pimento import menu
result = menu(['red', 'blue', 'green', 'grey'])

Prints:

Options:
  red
  blue
  green
  grey
Enter an option to continue:

Entering r results in red being returned from the function.

User input is matched case-sensitively from the beginning of each option. Ambiguous, null, and invalid entries are handled, an error message displayed, and the menu reprompted automatically.

This is the simplest, default usage. For more options, see the following example and the features list.

cli menu with all the features

  • custom pre-prompt
  • custom post-prompt
  • indexing
  • default selection
  • case-insensitivity
  • ‘fuzzy’ matching
  • deduplication
  • removal of empty items
from pimento import menu
result = menu(
  ['', 'RED', 'Red', 'blue', 'green', 'grey', 'green', 'light URPLE'],
  pre_prompt='Available colors:',
  post_prompt='Please select a color [{}]',
  default_index=3,
  indexed=True,
  insensitive=True,
  fuzzy=True
)

Prints:

Available colors:
  [0] RED
  [1] blue
  [2] green
  [3] grey
  [4] light URPLE
Please select a color [blue]:

Entering urple will result in the function returning light URPLE.

features

custom pre-prompt

You may specify any pre-prompt you wish to appear before the list of options:

from pimento import menu
result = menu(
  ['red', 'blue', 'green', 'grey'],
  pre_prompt="Which color?"
)

Prints:

Which color?
  red
  blue
  green
  grey
Enter an option to continue:

custom post-prompt

You may specify any post-propmt you wish to appear after the list of options:

from pimento import menu
result = menu(
  ['red', 'blue', 'green', 'grey'],
  post_prompt="Please select one: "
)

Prints:

Options:
  red
  blue
  green
  grey
Please select one:

partial matches

The user can select either a full option or a partial match. All of the following will result in the user selecting blue:

  • b
  • bl
  • blu
  • blue

re-prompting

When an invalid option is entered, an actionable error message is printed, and the menu is re-prompted.

when no choice is entered:

which color?
  red
  blue
  green
  grey
Please select one:
[!] an empty response is not valid.

when an invalid choice is entered:

which color?
  red
  blue
  green
  grey
Please select one: brown
[!] "brown" does not match any of the valid choices.

when an ambiguous choice is entered:

If gre was entered…

which color?
  red
  blue
  green
  grey
Please select one: gre
[!] "gre" matches multiple choices:
[!]   green
[!]   grey
[!] Please specify your choice further.

tab-completion

Tab completion of options is supported! At the moment, this is supported via readline, so this is a *nix-only feature. Arrow-key navigation of history and current line is also supported via the readline library.

using a default

menu will accept a default_index keyword argument. items[default_index] must be valid. An invalid index will result in an exception being raised at call time.

from pimento import menu
result = menu(
  ['red', 'blue', 'green'],
  "which color?",
  "Please select one [{}]: ",
  default_index=0
)

Prints:

which color?
  red
  blue
  green
Please select one [red]:

When a default_index is provided, it is valid to enter no value. In this case, the default value (red, in this example) is returned.

When a default_index is provided, if {} is present in the post-prompt, it will be replaced with the value of items[default_index]. It is recommended, but not required, that if you set a default_index, you should display the default value to the users via this substitution mechanism.

using indices

menu will accept an indexed argument. When set to True, indices will be printed with each option, and it will be valid to enter an index to choose an option.

from pimento import menu
result = menu(
  ['red', 'blue', 'green'],
  "which color?",
  "Please select one [{}]: ",
  default_index=0,
  indexed=True
)

Prints:

which color?
  [0] red
  [1] blue
  [2] green
Please select one [red]:

Choosing any of the following will return red:

  • <enter> (to select the default)
  • r
  • re
  • red
  • 0 (index)

When using indices, the selection is matched first by index, then by item. Given the following menu…

which number?
  [0] 100
  [1] 200
  [2] 300
Please select one:

…the selection/result pairs are:

  • 0 -> 100 (selection treated as index)
  • 1 -> 200 (selection treated as index)
  • 2 -> 300 (selection treated as index)
  • 3 -> 300 (selection matched no index, matched against items)
  • 10 -> 100 (selection matched no index, matched against items)
  • 20 -> 200 (selection matched no index, matched against items)
  • 30 -> 300 (selection matched no index, matched against items)

deduplication

If you pass multiple matching items into menu, it will deduplicate them for you. This is to prevent the following scenario:

pimento foo foo
Options:
  foo
  foo
Please select an option: foo
[!] "foo" matches multiple choices:
[!]   foo
[!]   foo
[!] Please specify your choice further.

You can’t specify a choice any further in this case, so pimento deduplicates the list for you. If you expect your list of items not to need deduplication, and you care about duplicates, you should check for them prior to calling menu.

The default index, if specified, will be used to select the default from the list prior to deduplication:

pimento bar foo foo -d 2
Options:
  bar
  foo
Please select an option [foo]: <enter>

In the above example, pimento prints ‘foo’ to stdout.

removal of empty items

If you pass empty items into menu, it will remove them for you. This is to prevent the following scenario:

pimento ''
Options:

Please select an option: <enter>
[!] an empty response is not valid.
Options:

Please select an option:

You can’t specify an empty choice, and an empty choice doesn’t make sense anyway, so pimento removes them for you. If all you had was empty choices, the call will fail with a ValueError about the list being empty. If you expect your list of items not to need removal of empty items, and you care if there are any, you should check that prior to calling menu.

The default index, if specified, will be used to select the default from the list prior to removal of empty items:

pimento '' bar foo -d 2
Options:
  bar
  foo
Please select an option [foo]: <enter>

In the above example, pimento prints ‘foo’ to stdout.

strips trailing whitespace

Trailing whitespace is stripped from each option passed in. A whitespace item is defined for pimento as it is by python - typically space, tab, newline, carriage return.

  • If stripping whitespace means that the item becomes a duplicate of another item, it will be removed according to the description in deduplication.
  • If it means that the item becomes empty it is removed according to the description in removal of empty items.

case-insensitivity

menu will accept an insensitive argument, which will make the menu match user input to the menu options in a case-insensitive manner.

from pimento import menu
result = menu(
  ['RED', 'Blue', 'green'],
  insensitive=True
)

Prints:

Options:
  RED
  Blue
  green
Enter an option to continue:

Entering red will get you RED, blue will get you Blue, and GREEN will get you green.

fuzzy matching

menu will accept a fuzzy argument, which will make the menu search for the words in the user input in the words of the item string, rather than just matching the user input from the start of the option:

from pimento import menu
result = menu(
  ['a blue thing', 'one green thing'],
  fuzzy=True
)

Prints:

Options:
  a blue thing
  one green thing
Enter an option to continue:

Entering thing n will return one green thing.

This method matches thing to both options (both contain the full word thing), then matches n only to one green thing, because that’s the only option with an unmatched n (in both one and green).

arrow keys

When running in a *nix environment, menu will use the Gnu readline library to provide support for command history and the use of arrow keys to edit entered text:

Options:
  foo
Enter an option to continue: oo
[!] "oo" does not match any of the valid choices.
Options:
  foo
Enter an option to continue: <up><left><left>f<enter>
foo

In the above example, the user hit <up>, which brought back ‘oo’ and put the cursor at the end. They then hit <left> twice to get the cursor back to the beginning of the word, inserted ‘f’ to spell the valid option ‘foo’, and hit enter.

CLI

There is a standalone CLI tool of the same name (pimento), which is a wrapper for pimento.menu, and can be used to create simple menus quickly on the command line:

pimento --help
usage: pimento [-h] [--pre TEXT] [--post TEXT] [--default-index INT]
               [--indexed]
               [option ...]

Present the user with a simple CLI menu, and return the option chosen. The
menu is presented via stderr. The output is printed to stdout for piping.

positional arguments:
  option                The option(s) to present to the user.

optional arguments:
  -h, --help            show this help message and exit
  --pre TEXT, -p TEXT   The pre-prompt/title/introduction to the menu.
                        [Options:]
  --post TEXT, -P TEXT  The prompt presented to the user after the menu items.
  --default-index INT, -d INT
                        The index of the item to use as the default
  --indexed, -i         Print indices with the options, and allow the user to
                        use them to choose.
  --insensitive, -I     Perform insensitive matching. Also drops any items
                        that case-insensitively match prior items.
  --fuzzy, -f           search for the individual words in the user input anywhere in the item strings.

The default for the post prompt is "Enter an option to continue: ". If
--default-index is specified, the default option value will be printed in the
post prompt as well.

On *nix, the CLI tool is capable of taking options from a pipe, like so:

echo -e 'foo\nbar' | pimento
Options:
  foo
  bar
Enter an option to continue:

installation

Latest pushed to Pypi (v0.7.1)

pip install pimento

Latest

pip install git+https://github.com/toejough/pimento

testing

pimento has been tested on python 2.7.9 and 3.4.3 on OSX. To test yourself:

git clone https://github.com/toejough/pimento
cd pimento
pip install tox
tox

API deprecation notices

Prompt ordering

Prior to version 0.4.0, the signature for menu was:

def menu(pre_prompt, items, post_prompt=DEFAULT, default_index=None, indexed=False):

In v0.4.0, the signature changed to:

def menu(items, pre_prompt=DEFAULT, post_prompt=DEFAULT, default_index=None, indexed=False):

To ease transition of any users, there is special code in place to determine which order the caller is passing in items and pre_prompt. All pre-0.4.0 code should continue to work, but passing pre_prompt as the first argument is a deprecated use and should be discontinued. Old code should be updated. The compatibility mode will be discontinued soon, but definitely by 1.0.0.

The API was changed to allow the simplest possible calling/use of the menu function. The original signature was chosen because I thought that there wasn’t a sensible default value, but “Options:” seems sensible enough for a generic default.

Search matching

As of version 0.6.0, the search method of matching is deprecated. It will be removed within a few releases, but definitely by v1.0.0.

fuzzy matching matches the same cases, and is more versatile.

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