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Click — composable CLI toolkit

Version: 8.1.7
Type: Pure Python
SPM target: Click
Auto-included by: Flask, Dash, manim, pip
Total Python modules: 17

Decorator-based command-line interface library. Flask's flask CLI, manim's manim CLI, and pip's argument parsing all run on Click. You rarely write a Click CLI for iOS (there's no shell to invoke it from), but it's a hard dependency of half the web/ML stack so it ships anyway. You can also use the underlying style/echo/prompt helpers from the in-app shell.

Modules

Module What it does
click.__init__ Public API — re-exports command, group, option, argument, echo, style, prompt, Context, Path, all ParamType subclasses, etc.
click.core Core classes: BaseCommand, Command, Group, Context, Parameter, Argument, Option, CommandCollection
click.decorators @command, @group, @option, @argument, @pass_context, @pass_obj, @make_pass_decorator, @version_option, @help_option, @password_option, @confirmation_option
click.types Built-in parameter types: STRING, INT, FLOAT, BOOL, UUID, Path, File, Choice, IntRange, FloatRange, DateTime, Tuple, UNPROCESSED
click.termui Terminal I/O: prompt, confirm, progressbar, style, secho, clear, pause, getchar, launch, edit, echo_via_pager
click.utils echo, format_filename, get_app_dir, LazyFile, KeepOpenFile, PacifyFlushWrapper
click.exceptions ClickException, UsageError, BadParameter, MissingParameter, NoSuchOption, BadOptionUsage, BadArgumentUsage, FileError, Abort, Exit
click.formatting HelpFormatter, wrap_text — help-text rendering
click.parser The argument parser used internally by Command.parse_args
click.testing CliRunner, Result — invoke commands in tests and capture stdout/stderr
click.shell_completion Bash/zsh/fish autocompletion script generation (not useful on iOS — no shell)
click.globals get_current_context, push_context, pop_context — thread-local context stack
click.types (Path, File) Smart path/file params with exists=, dir_okay=, writable=, automatic open/close
click._compat Stream encoding, Windows/Unix compat shims
click._termui_impl Internal helpers for termui (progress bar engine, pager invocation)
click._textwrap Help-text wrapping that respects ANSI escape codes
click._winconsole Windows console handling — unused on iOS
click._utils Internal sentinels (UNSET, FLAG_NEEDS_VALUE)

iOS notes

  • No shell to invoke from. Click CLIs work when called via CliRunner programmatically or from the in-app shell, but you don't get a global mycli command at the OS prompt.
  • prompt/confirm read from sys.stdin. In the in-app shell that's wired to the input field; in a script it'll block waiting for stdin that never arrives. Pass default= so non-interactive runs don't hang.
  • launch(url) opens via webbrowser.open which on iOS does nothing useful — use the host app's WKWebView instead.
  • edit() spawns $EDITOR, which doesn't exist on iOS. Don't use it.
  • progressbar writes to stderr with carriage returns — renders fine in the in-app shell.

Example

import click

@click.group()
def cli():
    """Toy CodeBench command group."""

@cli.command()
@click.option("--name", default="world", help="Who to greet")
@click.option("--count", "-n", default=1, type=int, help="Repeat N times")
def hello(name, count):
    for _ in range(count):
        click.secho(f"Hello, {name}!", fg="green", bold=True)

@cli.command()
@click.argument("path", type=click.Path(exists=True, dir_okay=False))
def show(path):
    with open(path) as f:
        click.echo_via_pager(f.read())

# Programmatic invocation (works on iOS, no shell needed)
from click.testing import CliRunner
result = CliRunner().invoke(cli, ["hello", "--name", "CodeBench", "-n", "2"])
print(result.output)