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epy.lazy_imports

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epy.lazy_imports#

etils.epy.lazy_imports(*, error_callback: str | Callable[[Exception], None] | None = None, success_callback: Callable[[str], None] | None = None) → Iterator[None][source]#

Context Manager which lazy loads packages.

Their import is not executed immediately, but is postponed to the first call of one of their attributes.

Limitation:

  • You can only lazy load modules (from x import y will not work if y is a constant or a function or a class).

Usage:

with epy.lazy_imports():
  import tensorflow as tf

with epy.lazy_imports(success_callback=check_tf_version):
  import tensorflow as tf

This support ecolab.adhoc imports: When the lazy-import is resolved, the original ecolab.adhoc context is re-created to import the lazy module.

Parameters:

  • error_callback – A additional message to append to the ImportError if the import fails. Can also be a Callable[[Exception], None]. The exception is passed as an arg, so user can use epy.reraise(e, ‘Additional message’).

  • success_callback – a callback to trigger when an import succeeds. The callback is passed the name of the imported module as an arg.

Yields:

None

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