This documentation is for a development version of Traitlets. There may be significant differences from the latest stable release.

Changes in Traitlets



4.3.2 on GitHub

4.3.2 is a tiny release, relaxing some of the deprecations introduced in 4.1:

  • using _traitname_default() without the @default decorator is no longer deprecated.
  • Passing config=True in traitlets constructors is no longer deprecated.


4.3.1 on GitHub

  • Compatibility fix for Python 3.6a1
  • Fix bug in Application.classes getting extra entries when multiple Applications are instantiated in the same process.


4.3.0 on GitHub

  • Improve the generated config file output.
  • Allow TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR env to override Application.raise_config_file_errors, so that config file errors can result in exiting immediately.
  • Avoid using root logger. If no application logger is registered, the 'traitlets' logger will be used instead of the root logger.
  • Change/Validation arguments are now Bunch objects, allowing attribute-access, in addition to dictionary access.
  • Reduce number of common deprecation messages in certain cases.
  • Ensure command-line options always have higher priority than config files.
  • Add bounds on numeric traits.
  • Improves various error messages.


4.2.2 - 2016-07-01

4.2.2 on GitHub

Partially revert a change in 4.1 that prevented IPython’s command-line options from taking priority over config files.

4.2.1 - 2016-03-14

4.2.1 on GitHub

Demotes warning about unused arguments in HasTraits.__init__ introduced in 4.2.0 to DeprecationWarning.

4.2.0 - 2016-03-14

4.2 on GitHub

  • JSONFileConfigLoader can be used as a context manager for updating configuration.
  • If a value in config does not map onto a configurable trait, a message is displayed that the value will have no effect.
  • Unused arguments are passed to super() in HasTraits.__init__, improving support for multiple inheritance.
  • Various bugfixes and improvements in the new API introduced in 4.1.
  • Application subclasses may specify raise_config_file_errors = True to exit on failure to load config files, instead of the default of logging the failures.

4.1 - 2016-01-15

4.1 on GitHub

Traitlets 4.1 introduces a totally new decorator-based API for configuring traitlets. Highlights:

  • Decorators are used, rather than magic method names, for registering trait-related methods. See Using Traitlets and Migration from Traitlets 4.0 to Traitlets 4.1 for more info.
  • Deprecate Trait(config=True) in favor of Trait().tag(config=True). In general, metadata is added via tag instead of the constructor.

Other changes:

  • Trait attributes initialized with read_only=True can only be set with the set_trait method. Attempts to directly modify a read-only trait attribute raises a TraitError.
  • The directional link now takes an optional transform attribute allowing the modification of the value.
  • Various fixes and improvements to config-file generation (fixed ordering, Undefined showing up, etc.)
  • Warn on unrecognized traits that aren’t configurable, to avoid silently ignoring mistyped config.

4.0 - 2015-06-19

4.0 on GitHub

First release of traitlets as a standalone package.