CHANGES.rst

.. currentmodule:: click

Version 8.1.0

Unreleased

• Single options boolean flags with show_default=True only show the default if it is True. :issue:`1971`:

Version 8.0.2

Unreleased

• is_bool_flag is not set to True if is_flag is False. :issue:`1925`
• Bash version detection is locale independent. :issue:`1940`
• Empty default value is not shown for multiple=True. :issue:`1969`
• Fix shell completion for arguments that start with a forward slash such as absolute file paths. :issue:`1929`
• Path type with resolve_path=True resolves relative symlinks to be relative to the containing directory. :issue:`1921`
• Completion does not skip Python's resource cleanup when exiting, avoiding some unexpected warning output. :issue:`1738, 2017`

Version 8.0.1

Released 2021-05-19

• Mark top-level names as exported so type checking understand imports in user projects. :issue:`1879`
• Annotate Context.obj as Any so type checking allows all operations on the arbitrary object. :issue:`1885`
• Fix some types that weren't available in Python 3.6.0. :issue:`1882`
• Fix type checking for iterating over ProgressBar object. :issue:`1892`
• The importlib_metadata backport package is installed on Python < 3.8. :issue:`1889`
• Arguments with nargs=-1 only use env var value if no command line values are given. :issue:`1903`
• Flag options guess their type from flag_value if given, like regular options do from default. :issue:`1886`
• Added documentation that custom parameter types may be passed already valid values in addition to strings. :issue:`1898`
• Resolving commands returns the name that was given, not command.name, fixing an unintended change to help text and default_map lookups. When using patterns like AliasedGroup, override resolve_command to change the name that is returned if needed. :issue:`1895`
• If a default value is invalid, it does not prevent showing help text. :issue:`1889`
• Pass windows_expand_args=False when calling the main command to disable pattern expansion on Windows. There is no way to escape patterns in CMD, so if the program needs to pass them on as-is then expansion must be disabled. :issue:`1901`

Version 8.0.0

Released 2021-05-11

• Drop support for Python 2 and 3.5.
• Colorama is always installed on Windows in order to provide style and color support. :pr:`1784`
• Adds a repr to Command, showing the command name for friendlier debugging. :issue:`1267`, :pr:`1295`
• Add support for distinguishing the source of a command line parameter. :issue:`1264`, :pr:`1329`
• Add an optional parameter to ProgressBar.update to set the current_item. :issue:`1226`, :pr:`1332`
• version_option uses importlib.metadata (or the importlib_metadata backport) instead of pkg_resources. The version is detected based on the package name, not the entry point name. The Python package name must match the installed package name, or be passed with package_name=. :issue:`1582`
• If validation fails for a prompt with hide_input=True, the value is not shown in the error message. :issue:`1460`
• An IntRange or FloatRange option shows the accepted range in its help text. :issue:`1525`, :pr:`1303`
• IntRange and FloatRange bounds can be open (<) instead of closed (<=) by setting min_open and max_open. Error messages have changed to reflect this. :issue:`1100`
• An option defined with duplicate flag names ("--foo/--foo") raises a ValueError. :issue:`1465`
• echo() will not fail when using pytest's capsys fixture on Windows. :issue:`1590`
• Resolving commands returns the canonical command name instead of the matched name. This makes behavior such as help text and Context.invoked_subcommand consistent when using patterns like AliasedGroup. :issue:`1422`
• The BOOL type accepts the values "on" and "off". :issue:`1629`
• A Group with invoke_without_command=True will always invoke its result callback. :issue:`1178`
• nargs == -1 and nargs > 1 is parsed and validated for values from environment variables and defaults. :issue:`729`
• Detect the program name when executing a module or package with python -m name. :issue:`1603`
• Include required parent arguments in help synopsis of subcommands. :issue:`1475`
• Help for boolean flags with show_default=True shows the flag name instead of True or False. :issue:`1538`
• Non-string objects passed to style() and secho() will be converted to string. :pr:`1146`
• edit(require_save=True) will detect saves for editors that exit very fast on filesystems with 1 second resolution. :pr:`1050`
• New class attributes make it easier to use custom core objects throughout an entire application. :pr:`938`
  • Command.context_class controls the context created when running the command.
  • Context.invoke creates new contexts of the same type, so a custom type will persist to invoked subcommands.
  • Context.formatter_class controls the formatter used to generate help and usage.
  • Group.command_class changes the default type for subcommands with @group.command().
  • Group.group_class changes the default type for subgroups with @group.group(). Setting it to type will create subgroups of the same type as the group itself.
  • Core objects use super() consistently for better support of subclassing.
• Use Context.with_resource() to manage resources that would normally be used in a with statement, allowing them to be used across subcommands and callbacks, then cleaned up when the context ends. :pr:`1191`
• The result object returned by the test runner's invoke() method has a return_value attribute with the value returned by the invoked command. :pr:`1312`
• Required arguments with the Choice type show the choices in curly braces to indicate that one is required ({a|b|c}). :issue:`1272`
• If only a name is passed to option(), Click suggests renaming it to --name. :pr:`1355`
• A context's show_default parameter defaults to the value from the parent context. :issue:`1565`
• click.style() can output 256 and RGB color codes. Most modern terminals support these codes. :pr:`1429`
• When using CliRunner.invoke(), the replaced stdin file has name and mode attributes. This lets File options with the - value match non-testing behavior. :issue:`1064`
• When creating a Group, allow passing a list of commands instead of a dict. :issue:`1339`
• When a long option name isn't valid, use difflib to make better suggestions for possible corrections. :issue:`1446`
• Core objects have a to_info_dict() method. This gathers information about the object's structure that could be useful for a tool generating user-facing documentation. To get the structure of an entire CLI, use Context(cli).to_info_dict(). :issue:`461`
• Redesign the shell completion system. :issue:`1484`, :pr:`1622`
  • Support Bash >= 4.4, Zsh, and Fish, with the ability for extensions to add support for other shells.
  • Allow commands, groups, parameters, and types to override their completions suggestions.
  • Groups complete the names commands were registered with, which can differ from the name they were created with.
  • The autocompletion parameter for options and arguments is renamed to shell_complete. The function must take ctx, param, incomplete, must do matching rather than return all values, and must return a list of strings or a list of CompletionItem. The old name and behavior is deprecated and will be removed in 8.1.
  • The env var values used to start completion have changed order. The shell now comes first, such as {shell}_source rather than source_{shell}, and is always required.
• Completion correctly parses command line strings with incomplete quoting or escape sequences. :issue:`1708`
• Extra context settings (obj=..., etc.) are passed on to the completion system. :issue:`942`
• Include --help option in completion. :pr:`1504`
• ParameterSource is an enum.Enum subclass. :issue:`1530`
• Boolean and UUID types strip surrounding space before converting. :issue:`1605`
• Adjusted error message from parameter type validation to be more consistent. Quotes are used to distinguish the invalid value. :issue:`1605`
• The default value for a parameter with nargs > 1 and multiple=True must be a list of tuples. :issue:`1649`
• When getting the value for a parameter, the default is tried in the same section as other sources to ensure consistent processing. :issue:`1649`
• All parameter types accept a value that is already the correct type. :issue:`1649`
• For shell completion, an argument is considered incomplete if its value did not come from the command line args. :issue:`1649`
• Added ParameterSource.PROMPT to track parameter values that were prompted for. :issue:`1649`
• Options with nargs > 1 no longer raise an error if a default is not given. Parameters with nargs > 1 default to None, and parameters with multiple=True or nargs=-1 default to an empty tuple. :issue:`472`
• Handle empty env vars as though the option were not passed. This extends the change introduced in 7.1 to be consistent in more cases. :issue:`1285`
• Parameter.get_default() checks Context.default_map to handle overrides consistently in help text, invoke(), and prompts. :issue:`1548`
• Add prompt_required param to Option. When set to False, the user will only be prompted for an input if no value was passed. :issue:`736`
• Providing the value to an option can be made optional through is_flag=False, and the value can instead be prompted for or passed in as a default value. :issue:`549, 736, 764, 921, 1015, 1618`
• Fix formatting when Command.options_metavar is empty. :pr:`1551`
• Revert adding space between option help text that wraps. :issue:`1831`
• The default value passed to prompt will be cast to the correct type like an input value would be. :pr:`1517`
• Automatically generated short help messages will stop at the first ending of a phrase or double linebreak. :issue:`1082`
• Skip progress bar render steps for efficiency with very fast iterators by setting update_min_steps. :issue:`676`
• Respect case_sensitive=False when doing shell completion for Choice :issue:`1692`
• Use mkstemp() instead of mktemp() in pager implementation. :issue:`1752`
• If Option.show_default is a string, it is displayed even if default is None. :issue:`1732`
• click.get_terminal_size() is deprecated and will be removed in 8.1. Use :func:`shutil.get_terminal_size` instead. :issue:`1736`
• Control the location of the temporary directory created by CLIRunner.isolated_filesystem by passing temp_dir. A custom directory will not be removed automatically. :issue:`395`
• click.confirm() will prompt until input is given if called with default=None. :issue:`1381`
• Option prompts validate the value with the option's callback in addition to its type. :issue:`457`
• confirmation_prompt can be set to a custom string. :issue:`723`
• Allow styled output in Jupyter on Windows. :issue:`1271`
• style() supports the strikethrough, italic, and overline styles. :issue:`805, 1821`
• Multiline marker is removed from short help text. :issue:`1597`
• Restore progress bar behavior of echoing only the label if the file is not a TTY. :issue:`1138`
• Progress bar output is shown even if execution time is less than 0.5 seconds. :issue:`1648`
• Progress bar item_show_func shows the current item, not the previous item. :issue:`1353`
• The Path param type can be passed path_type=pathlib.Path to return a path object instead of a string. :issue:`405`
• TypeError is raised when parameter with multiple=True or nargs > 1 has non-iterable default. :issue:`1749`
• Add a pass_meta_key decorator for passing a key from Context.meta. This is useful for extensions using meta to store information. :issue:`1739`
• Path resolve_path resolves symlinks on Windows Python < 3.8. :issue:`1813`
• Command deprecation notice appears at the start of the help text, as well as in the short help. The notice is not in all caps. :issue:`1791`
• When taking arguments from sys.argv on Windows, glob patterns, user dir, and env vars are expanded. :issue:`1096`
• Marked messages shown by the CLI with gettext() to allow applications to translate Click's built-in strings. :issue:`303`
• Writing invalid characters to stderr when using the test runner does not raise a UnicodeEncodeError. :issue:`848`
• Fix an issue where readline would clear the entire prompt() line instead of only the input when pressing backspace. :issue:`665`
• Add all kwargs passed to Context.invoke() to ctx.params. Fixes an inconsistency when nesting Context.forward() calls. :issue:`1568`
• The MultiCommand.resultcallback decorator is renamed to result_callback. The old name is deprecated. :issue:`1160`
• Fix issues with CliRunner output when using echo_stdin=True. :issue:`1101`
• Fix a bug of click.utils.make_default_short_help for which the returned string could be as long as max_width + 3. :issue:`1849`
• When defining a parameter, default is validated with multiple and nargs. More validation is done for values being processed as well. :issue:`1806`
• HelpFormatter.write_text uses the full line width when wrapping text. :issue:`1871`

Version 7.1.2

Released 2020-04-27

• Revert applying shell quoting to commands for echo_with_pager and edit. This was intended to allows spaces in commands, but caused issues if the string was actually a command and arguments, or on Windows. Instead, the string must be quoted manually as it should appear on the command line. :issue:`1514`

Version 7.1.1

Released 2020-03-09

• Fix ClickException output going to stdout instead of stderr. :issue:`1495`

Version 7.1

Released 2020-03-09

• Fix PyPI package name, "click" is lowercase again.
• Fix link in unicode_literals error message. :pr:`1151`
• Add support for colored output on UNIX Jupyter notebooks. :issue:`1185`
• Operations that strip ANSI controls will strip the cursor hide/show sequences. :issue:`1216`
• Remove unused compat shim for bytes. :pr:`1195`
• Expand testing around termui, especially getchar on Windows. :issue:`1116`
• Fix output on Windows Python 2.7 built with MSVC 14. :pr:`1342`
• Fix OSError when running in MSYS2. :issue:`1338`
• Fix OSError when redirecting to NUL stream on Windows. :issue:`1065`
• Fix memory leak when parsing Unicode arguments on Windows. :issue:`1136`
• Fix error in new AppEngine environments. :issue:`1462`
• Always return one of the passed choices for click.Choice :issue:`1277`, :pr:`1318`
• Add no_args_is_help option to click.Command, defaults to False :pr:`1167`
• Add show_default parameter to Context to enable showing defaults globally. :issue:`1018`
• Handle env MYPATH='' as though the option were not passed. :issue:`1196`
• It is once again possible to call next(bar) on an active progress bar instance. :issue:`1125`
• open_file with atomic=True retains permissions of existing files and respects the current umask for new files. :issue:`1376`
• When using the test CliRunner with mix_stderr=False, if result.stderr is empty it will not raise a ValueError. :issue:`1193`
• Remove the unused mix_stderr parameter from CliRunner.invoke. :issue:`1435`
• Fix TypeError raised when using bool flags and specifying type=bool. :issue:`1287`
• Newlines in option help text are replaced with spaces before re-wrapping to avoid uneven line breaks. :issue:`834`
• MissingParameter exceptions are printable in the Python interpreter. :issue:`1139`
• Fix how default values for file-type options are shown during prompts. :issue:`914`
• Fix environment variable automatic generation for commands containing -. :issue:`1253`
• Option help text replaces newlines with spaces when rewrapping, but preserves paragraph breaks, fixing multiline formatting. :issue:`834, 1066, 1397`
• Option help text that is wrapped adds an extra newline at the end to distinguish it from the next option. :issue:`1075`
• Consider sensible-editor when determining the editor to use for click.edit(). :pr:`1469`
• Arguments to system calls such as the executable path passed to click.edit can contains spaces. :pr:`1470`
• Add ZSH completion autoloading and error handling. :issue:`1348`
• Add a repr to Command, Group, Option, and Argument, showing the name for friendlier debugging. :issue:`1267`
• Completion doesn't consider option names if a value starts with - after the -- separator. :issue:`1247`
• ZSH completion escapes special characters in values. :pr:`1418`
• Add completion support for Fish shell. :pr:`1423`
• Decoding bytes option values falls back to UTF-8 in more cases. :pr:`1468`
• Make the warning about old 2-arg parameter callbacks a deprecation warning, to be removed in 8.0. This has been a warning since Click 2.0. :pr:`1492`
• Adjust error messages to standardize the types of quotes used so they match error messages from Python.

Version 7.0

Released 2018-09-25

• Drop support for Python 2.6 and 3.3. :pr:`967, 976`
• Wrap click.Choice's missing message. :issue:`202`, :pr:`1000`
• Add native ZSH autocompletion support. :issue:`323`, :pr:`865`
• Document that ANSI color info isn't parsed from bytearrays in Python 2. :issue:`334`
• Document byte-stripping behavior of CliRunner. :issue:`334`, :pr:`1010`
• Usage errors now hint at the --help option. :issue:`393`, :pr:`557`
• Implement streaming pager. :issue:`409`, :pr:`889`
• Extract bar formatting to its own method. :pr:`414`
• Add DateTime type for converting input in given date time formats. :pr:`423`
• secho's first argument can now be None, like in echo. :pr:`424`
• Fixes a ZeroDivisionError in ProgressBar.make_step, when the arg passed to the first call of ProgressBar.update is 0. :issue:`447`, :pr:`1012`
• Show progressbar only if total execution time is visible. :pr:`487`
• Added the ability to hide commands and options from help. :pr:`500`
• Document that options can be required=True. :issue:`514`, :pr:`1022`
• Non-standalone calls to Context.exit return the exit code, rather than calling sys.exit. :issue:`667`, :pr:`533, 1098`
• click.getchar() returns Unicode in Python 3 on Windows, consistent with other platforms. :issue:`537, 821, 822, 1088`, :pr:`1108`
• Added FloatRange type. :pr:`538, 553`
• Added support for bash completion of type=click.Choice for Options and Arguments. :issue:`535`, :pr:`681`
• Only allow one positional arg for Argument parameter declaration. :issue:`568, 574`, :pr:`1014`
• Add case_sensitive=False as an option to Choice. :issue:`569`
• click.getchar() correctly raises KeyboardInterrupt on "^C" and EOFError on "^D" on Linux. :issue:`583`, :pr:`1115`
• Fix encoding issue with click.getchar(echo=True) on Linux. :pr:`1115`
• param_hint in errors now derived from param itself. :issue:`598, 704`, :pr:`709`
• Add a test that ensures that when an argument is formatted into a usage error, its metavar is used, not its name. :pr:`612`
• Allow setting prog_name as extra in CliRunner.invoke. :issue:`616`, :pr:`999`
• Help text taken from docstrings truncates at the \f form feed character, useful for hiding Sphinx-style parameter documentation. :pr:`629, 1091`
• launch now works properly under Cygwin. :pr:`650`
• Update progress after iteration. :issue:`651`, :pr:`706`
• CliRunner.invoke now may receive args as a string representing a Unix shell command. :pr:`664`
• Make Argument.make_metavar() default to type metavar. :pr:`675`
• Add documentation for ignore_unknown_options. :pr:`684`
• Add bright colors support for click.style and fix the reset option for parameters fg and bg. :issue:`703`, :pr:`809`
• Add show_envvar for showing environment variables in help. :pr:`710`
• Avoid BrokenPipeError during interpreter shutdown when stdout or stderr is a closed pipe. :issue:`712`, :pr:`1106`
• Document customizing option names. :issue:`725`, :pr:`1016`
• Disable sys._getframes() on Python interpreters that don't support it. :pr:`728`
• Fix bug in test runner when calling sys.exit with None. :pr:`739`
• Clarify documentation on command line options. :issue:`741`, :pr:`1003`
• Fix crash on Windows console. :issue:`744`
• Fix bug that caused bash completion to give improper completions on chained commands. :issue:`754`, :pr:`774`
• Added support for dynamic bash completion from a user-supplied callback. :pr:`755`
• Added support for bash completions containing spaces. :pr:`773`
• Allow autocompletion function to determine whether or not to return completions that start with the incomplete argument. :issue:`790`, :pr:`806`
• Fix option naming routine to match documentation and be deterministic. :issue:`793`, :pr:`794`
• Fix path validation bug. :issue:`795`, :pr:`1020`
• Add test and documentation for Option naming: functionality. :pr:`799`
• Update doc to match arg name for path_type. :pr:`801`
• Raw strings added so correct escaping occurs. :pr:`807`
• Fix 16k character limit of click.echo on Windows. :issue:`816`, :pr:`819`
• Overcome 64k character limit when writing to binary stream on Windows 7. :issue:`825`, :pr:`830`
• Add bool conversion for "t" and "f". :pr:`842`
• NoSuchOption errors take ctx so that --help hint gets printed in error output. :pr:`860`
• Fixed the behavior of Click error messages with regards to Unicode on 2.x and 3.x. Message is now always Unicode and the str and Unicode special methods work as you expect on that platform. :issue:`862`
• Progress bar now uses stderr by default. :pr:`863`
• Add support for auto-completion documentation. :issue:`866`, :pr:`869`
• Allow CliRunner to separate stdout and stderr. :pr:`868`
• Fix variable precedence. :issue:`873`, :pr:`874`
• Fix invalid escape sequences. :pr:`877`
• Fix ResourceWarning that occurs during some tests. :pr:`878`
• When detecting a misconfigured locale, don't fail if the locale command fails. :pr:`880`
• Add case_sensitive=False as an option to Choice types. :pr:`887`
• Force stdout/stderr writable. This works around issues with badly patched standard streams like those from Jupyter. :pr:`918`
• Fix completion of subcommand options after last argument :issue:`919`, :pr:`930`
• _AtomicFile now uses the realpath of the original filename so that changing the working directory does not affect it. :pr:`920`
• Fix incorrect completions when defaults are present :issue:`925`, :pr:`930`
• Add copy option attrs so that custom classes can be re-used. :issue:`926`, :pr:`994`
• "x" and "a" file modes now use stdout when file is "-". :pr:`929`
• Fix missing comma in __all__ list. :pr:`935`
• Clarify how parameters are named. :issue:`949`, :pr:`1009`
• Stdout is now automatically set to non blocking. :pr:`954`
• Do not set options twice. :pr:`962`
• Move fcntl import. :pr:`965`
• Fix Google App Engine ImportError. :pr:`995`
• Better handling of help text for dynamic default option values. :pr:`996`
• Fix get_winter_size() so it correctly returns (0,0). :pr:`997`
• Add test case checking for custom param type. :pr:`1001`
• Allow short width to address cmd formatting. :pr:`1002`
• Add details about Python version support. :pr:`1004`
• Added deprecation flag to commands. :pr:`1005`
• Fixed issues where fd was undefined. :pr:`1007`
• Fix formatting for short help. :pr:`1008`
• Document how auto_envvar_prefix works with command groups. :pr:`1011`
• Don't add newlines by default for progress bars. :pr:`1013`
• Use Python sorting order for ZSH completions. :issue:`1047`, :pr:`1059`
• Document that parameter names are converted to lowercase by default. :pr:`1055`
• Subcommands that are named by the function now automatically have the underscore replaced with a dash. If you register a function named my_command it becomes my-command in the command line interface.
• Hide hidden commands and options from completion. :issue:`1058`, :pr:`1061`
• Fix absolute import blocking Click from being vendored into a project on Windows. :issue:`1068`, :pr:`1069`
• Fix issue where a lowercase auto_envvar_prefix would not be converted to uppercase. :pr:`1105`

Version 6.7

Released 2017-01-06

• Make click.progressbar work with codecs.open files. :pr:`637`
• Fix bug in bash completion with nested subcommands. :pr:`639`
• Fix test runner not saving caller env correctly. :pr:`644`
• Fix handling of SIGPIPE. :pr:`62`
• Deal with broken Windows environments such as Google App Engine's. :issue:`711`

Version 6.6

Released 2016-04-04

• Fix bug in click.Path where it would crash when passed a -. :issue:`551`

Version 6.4

Released 2016-03-24

• Fix bug in bash completion where click would discard one or more trailing arguments. :issue:`471`

Version 6.3

Released 2016-02-22

• Fix argument checks for interpreter invoke with -m and -c on Windows.
• Fixed a bug that cased locale detection to error out on Python 3.

Version 6.2

Released 2015-11-27

• Correct fix for hidden progress bars.

Version 6.1

Released 2015-11-27

• Resolved an issue with invisible progress bars no longer rendering.
• Disable chain commands with subcommands as they were inherently broken.
• Fix MissingParameter not working without parameters passed.

Version 6.0

Released 2015-11-24, codename "pow pow"

• Optimized the progressbar rendering to not render when it did not actually change.
• Explicitly disallow nargs=-1 with a set default.
• The context is now closed before it's popped from the stack.
• Added support for short aliases for the false flag on toggles.
• Click will now attempt to aid you with debugging locale errors better by listing with the help of the OS what locales are available.
• Click used to return byte strings on Python 2 in some unit-testing situations. This has been fixed to correctly return unicode strings now.
• For Windows users on Python 2, Click will now handle Unicode more correctly handle Unicode coming in from the system. This also has the disappointing side effect that filenames will now be always unicode by default in the Path type which means that this can introduce small bugs for code not aware of this.
• Added a type parameter to Path to force a specific string type on the value.
• For users running Python on Windows the echo and prompt functions now work with full unicode functionality in the Python windows console by emulating an output stream. This also applies to getting the virtual output and input streams via click.get_text_stream(...).
• Unittests now always force a certain virtual terminal width.
• Added support for allowing dashes to indicate standard streams to the Path type.
• Multi commands in chain mode no longer propagate arguments left over from parsing to the callbacks. It's also now disallowed through an exception when optional arguments are attached to multi commands if chain mode is enabled.
• Relaxed restriction that disallowed chained commands to have other chained commands as child commands.
• Arguments with positive nargs can now have defaults implemented. Previously this configuration would often result in slightly unexpected values be returned.

Version 5.1

Released 2015-08-17

• Fix a bug in pass_obj that would accidentally pass the context too.

Version 5.0

Released 2015-08-16, codename "tok tok"

• Removed various deprecated functionality.
• Atomic files now only accept the w mode.
• Change the usage part of help output for very long commands to wrap their arguments onto the next line, indented by 4 spaces.
• Fix a bug where return code and error messages were incorrect when using CliRunner.
• Added get_current_context.
• Added a meta dictionary to the context which is shared across the linked list of contexts to allow click utilities to place state there.
• Introduced Context.scope.
• The echo function is now threadsafe: It calls the write method of the underlying object only once.
• prompt(hide_input=True) now prints a newline on ^C.
• Click will now warn if users are using unicode_literals.
• Click will now ignore the PAGER environment variable if it is empty or contains only whitespace.
• The click-contrib GitHub organization was created.

Version 4.1

Released 2015-07-14

• Fix a bug where error messages would include a trailing None string.
• Fix a bug where Click would crash on docstrings with trailing newlines.
• Support streams with encoding set to None on Python 3 by barfing with a better error.
• Handle ^C in less-pager properly.
• Handle return value of None from sys.getfilesystemencoding
• Fix crash when writing to unicode files with click.echo.
• Fix type inference with multiple options.

Version 4.0

Released 2015-03-31, codename "zoom zoom"

• Added color parameters to lots of interfaces that directly or indirectly call into echoing. This previously was always autodetection (with the exception of the echo_via_pager function). Now you can forcefully enable or disable it, overriding the auto detection of Click.
• Added an UNPROCESSED type which does not perform any type changes which simplifies text handling on 2.x / 3.x in some special advanced usecases.
• Added NoSuchOption and BadOptionUsage exceptions for more generic handling of errors.
• Added support for handling of unprocessed options which can be useful in situations where arguments are forwarded to underlying tools.
• Added max_content_width parameter to the context which can be used to change the maximum width of help output. By default Click will not format content for more than 80 characters width.
• Added support for writing prompts to stderr.
• Fix a bug when showing the default for multiple arguments.
• Added support for custom subclasses to option and argument.
• Fix bug in clear() on Windows when colorama is installed.
• Reject nargs=-1 for options properly. Options cannot be variadic.
• Fixed an issue with bash completion not working properly for commands with non ASCII characters or dashes.
• Added a way to manually update the progressbar.
• Changed the formatting of missing arguments. Previously the internal argument name was shown in error messages, now the metavar is shown if passed. In case an automated metavar is selected, it's stripped of extra formatting first.

Version 3.3

Released 2014-09-08

• Fixed an issue with error reporting on Python 3 for invalid forwarding of commands.

Version 3.2

Released 2014-08-22

• Added missing err parameter forwarding to the secho function.
• Fixed default parameters not being handled properly by the context invoke method. This is a backwards incompatible change if the function was used improperly. See :ref:`upgrade-to-3.2` for more information.
• Removed the invoked_subcommands attribute largely. It is not possible to provide it to work error free due to how the parsing works so this API has been deprecated. See :ref:`upgrade-to-3.2` for more information.
• Restored the functionality of invoked_subcommand which was broken as a regression in 3.1.

Version 3.1

Released 2014-08-13

• Fixed a regression that caused contexts of subcommands to be created before the parent command was invoked which was a regression from earlier Click versions.

Version 3.0

Released 2014-08-12, codename "clonk clonk"

• Formatter now no longer attempts to accommodate for terminals smaller than 50 characters. If that happens it just assumes a minimal width.
• Added a way to not swallow exceptions in the test system.
• Added better support for colors with pagers and ways to override the autodetection.
• The CLI runner's result object now has a traceback attached.
• Improved automatic short help detection to work better with dots that do not terminate sentences.
• When defining options without actual valid option strings now, Click will give an error message instead of silently passing. This should catch situations where users wanted to created arguments instead of options.
• Restructured Click internally to support vendoring.
• Added support for multi command chaining.
• Added support for defaults on options with multiple and options and arguments with nargs != 1.
• Label passed to progressbar is no longer rendered with whitespace stripped.
• Added a way to disable the standalone mode of the main method on a Click command to be able to handle errors better.
• Added support for returning values from command callbacks.
• Added simplifications for printing to stderr from echo.
• Added result callbacks for groups.
• Entering a context multiple times defers the cleanup until the last exit occurs.
• Added open_file.

Version 2.6

Released 2014-08-11

• Fixed an issue where the wrapped streams on Python 3 would be reporting incorrect values for seekable.

Version 2.5

Released 2014-07-28

• Fixed a bug with text wrapping on Python 3.

Version 2.4

Released 2014-07-04

• Corrected a bug in the change of the help option in 2.3.

Version 2.3

Released 2014-07-03

• Fixed an incorrectly formatted help record for count options.
• Add support for ansi code stripping on Windows if colorama is not available.
• Restored the Click 1.0 handling of the help parameter for certain edge cases.

Version 2.2

Released 2014-06-26

• Fixed tty detection on PyPy.
• Fixed an issue that progress bars were not rendered when the context manager was entered.

Version 2.1

Released 2014-06-14

• Fixed the :func:`launch` function on windows.
• Improved the colorama support on windows to try hard to not screw up the console if the application is interrupted.
• Fixed windows terminals incorrectly being reported to be 80 characters wide instead of 79
• Use colorama win32 bindings if available to get the correct dimensions of a windows terminal.
• Fixed an issue with custom function types on Python 3.
• Fixed an issue with unknown options being incorrectly reported in error messages.

Version 2.0

Released 2014-06-06, codename "tap tap tap"

• Added support for opening stdin/stdout on Windows in binary mode correctly.
• Added support for atomic writes to files by going through a temporary file.
• Introduced :exc:`BadParameter` which can be used to easily perform custom validation with the same error messages as in the type system.
• Added :func:`progressbar`; a function to show progress bars.
• Added :func:`get_app_dir`; a function to calculate the home folder for configs.
• Added transparent handling for ANSI codes into the :func:`echo` function through colorama.
• Added :func:`clear` function.
• Breaking change: parameter callbacks now get the parameter object passed as second argument. There is legacy support for old callbacks which will warn but still execute the script.
• Added :func:`style`, :func:`unstyle` and :func:`secho` for ANSI styles.
• Added an :func:`edit` function that invokes the default editor.
• Added an :func:`launch` function that launches browsers and applications.
• Nargs of -1 for arguments can now be forced to be a single item through the required flag. It defaults to not required.
• Setting a default for arguments now implicitly makes it non required.
• Changed "yN" / "Yn" to "y/N" and "Y/n" in confirmation prompts.
• Added basic support for bash completion.
• Added :func:`getchar` to fetch a single character from the terminal.
• Errors now go to stderr as intended.
• Fixed various issues with more exotic parameter formats like DOS/Windows style arguments.
• Added :func:`pause` which works similar to the Windows pause cmd built-in but becomes an automatic noop if the application is not run through a terminal.
• Added a bit of extra information about missing choice parameters.
• Changed how the help function is implemented to allow global overriding of the help option.
• Added support for token normalization to implement case insensitive handling.
• Added support for providing defaults for context settings.

Version 1.1

Released 2014-05-23

• Fixed a bug that caused text files in Python 2 to not accept native strings.

Version 1.0

Released 2014-05-21

• Initial release.