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--- python:decorators [2024/08/30 16:22] – created, page about decorators. Niels
+++ python:decorators [2024/09/30 08:09] (current) – Niels
@@ Line 1: / Line 1: @@
 ====== Decorators ======
-Decorators add behaviour to existing functions. They are bascially functions wrapping around the function being decorated.
+Decorators extend functions, methods, classes without explicitly modifying the code of the item being decorated.
-the implementation of a decorator takes care of passing arguments to a inner decorator function which defines the logic
+example of a decorator //Italic (skelleton structure only)//:
-that the decorator is supposed to add and calls the original function.
+<code python>
+def decorator_function(func):
+    ''' Receives the function being decorated as first argument'''
+    def actual_decorator(*args, **kwargs):
+        '''function that actually performs the decorated logic '''
+        # do something, before original logic
+        #call the original function
+        func(*args,**kwargs)
+        # and/or do something after.
+        #return result
+    #return the actual decorator so it gets called by calling context .
+    return actual_decorator
+</code>
+example of decorator with arguments//Italic (skelleton structure only)//:
+<code python>
+def decorator_function(a, b):
+    ''' Receives the decorator arguments'''
+    def additional_wrapper(func):
+        ''' receivs the function (and its arguments) being decorated '''
+        def actual_decorator(*args, **kwargs):
+            '''function that actually performs the decorated logic '''
+            #arguments a and b passed from outer fuction are in scope but read only.
+               if a > b:
+                   pass
+            # do something, before original logic
+            #call the original function
+            func(*args,**kwargs)
+            # and/or do something after.
+            #return result
+        # return function to calling context (so that it gets executed).
+        return actual_decorator
+    #return fuction to calling context (so that it gets executed).
+    return additional_wrapper
+</code>
-Than the decorator returns a reference to its inner function.
-So the decorator itself does not execute the decorator logic, the calling context does!
 **Related:**
@@ Line 13: / Line 62: @@
   *[[https://pybit.es/articles/decorators-by-example/ | Learning Python Decorators by Example (pybit.es)]]
   *[[https://wiki.python.org/moin/PythonDecorators| PythonDecorators (wiki.python.org)]]
+  *[[https://builtin.com/software-engineering-perspectives/python-class-decorator| Using Python Class Decorators (builtin.com)]]
+  *[[https://realpython.com/python-metaclasses/| Python Metaclasses (realpython.com)]]((With metaclasses you can define how classes are created.))
+  *[[https://realpython.com/primer-on-python-decorators/| Primer on Python decorators (realpython.com)]]
+  *[[https://python-reference.readthedocs.io/en/latest/docs/functions/property.html | article on property decorator]]
 {{tag>python development decorators}}

Niels Notes

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