Source code for cookiecutter.environment

"""Jinja2 environment and extensions loading."""

from jinja2 import Environment, StrictUndefined

from cookiecutter.exceptions import UnknownExtension

[docs] class ExtensionLoaderMixin: """Mixin providing sane loading of extensions specified in a given context. The context is being extracted from the keyword arguments before calling the next parent class in line of the child. """ def __init__(self, **kwargs): """Initialize the Jinja2 Environment object while loading extensions. Does the following: 1. Establishes default_extensions (currently just a Time feature) 2. Reads extensions set in the cookiecutter.json _extensions key. 3. Attempts to load the extensions. Provides useful error if fails. """ context = kwargs.pop('context', {}) default_extensions = [ 'cookiecutter.extensions.JsonifyExtension', 'cookiecutter.extensions.RandomStringExtension', 'cookiecutter.extensions.SlugifyExtension', 'cookiecutter.extensions.TimeExtension', 'cookiecutter.extensions.UUIDExtension', ] extensions = default_extensions + self._read_extensions(context) try: super().__init__(extensions=extensions, **kwargs) except ImportError as err: raise UnknownExtension(f'Unable to load extension: {err}') from err def _read_extensions(self, context): """Return list of extensions as str to be passed on to the Jinja2 env. If context does not contain the relevant info, return an empty list instead. """ try: extensions = context['cookiecutter']['_extensions'] except KeyError: return [] else: return [str(ext) for ext in extensions]
[docs] class StrictEnvironment(ExtensionLoaderMixin, Environment): """Create strict Jinja2 environment. Jinja2 environment will raise error on undefined variable in template- rendering context. """ def __init__(self, **kwargs): """Set the standard Cookiecutter StrictEnvironment. Also loading extensions defined in cookiecutter.json's _extensions key. """ super().__init__(undefined=StrictUndefined, **kwargs)