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bpo-32192: A basic lazy importer example (GH-21330) 

* Add example on lazy imports

* Use four spaces for indentation

* change to console
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Joannah Nanjekye 2020-07-13 18:31:02 -03:00 committed by GitHub
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Doc/library/importlib.rst
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@ -1719,6 +1719,29 @@ To import a Python source file directly, use the following recipe
spec.loader.exec_module(module)
Implementing lazy imports
'''''''''''''''''''''''''
The example below shows how to implement lazy imports::
>>> import importlib.util
>>> import sys
>>> def lazy_import(name):
... spec = importlib.util.find_spec(name)
... loader = importlib.util.LazyLoader(spec.loader)
... spec.loader = loader
... module = importlib.util.module_from_spec(spec)
... sys.modules[name] = module
... loader.exec_module(module)
... return module
...
>>> lazy_typing = lazy_import("typing")
>>> #lazy_typing is a real module object,
>>> #but it is not loaded in memory yet.
>>> lazy_typing.TYPE_CHECKING
False
Setting up an importer
''''''''''''''''''''''