From: Joannah Nanjekye <33177550+nanjekyejoannah@users.noreply.github.com>
Date: Mon, 13 Jul 2020 21:31:02 +0000 (-0300)
Subject: bpo-32192: A basic lazy importer example (GH-21330)
X-Git-Tag: v3.10.0a1~398
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8dd32fe645c9503cf8e6be4b1580c3a59b450168;p=thirdparty%2FPython%2Fcpython.git

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

* Add example on lazy imports

* Use four spaces for indentation

* change to console
---

diff --git a/Doc/library/importlib.rst b/Doc/library/importlib.rst
index 99bfeacbbc74..f7286d2ade8b 100644
--- a/Doc/library/importlib.rst
+++ b/Doc/library/importlib.rst
@@ -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
 ''''''''''''''''''''''