mrtj · May 13, 2022 21:10 · May 13, 2022
diff --git a/lazy_property.py b/lazy_property.py
@@ -0,0 +1,29 @@
+import functools
+
+def lazy_property(func):
+    ''' Caches the return value of a function, and turns it into a property. 
+    
+    Intended to be used as a function decorator::
+    
+        >>> class Foo:
+        >>>     @lazy_property
+        >>>     def bar(self):
+        >>>         print('expensive calculation')
+        >>>         return 'bar'
+        >>> foo = Foo()
+        >>> foo.bar()
+        expensive calculation
+        'bar'
+        >>> foo.bar()
+        'bar'
+    '''
+    attrib_name = '_' + func.__name__
+    @property
+    @functools.wraps(func)
+    def lazy_wrapper(instance, *args, **kwargs):
+        if hasattr(instance, attrib_name):
+            return getattr(instance, attrib_name)
+        value = func(instance, *args, **kwargs)
+        object.__setattr__(instance, attrib_name, value)
+        return value
+    return lazy_wrapper
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