It took me quite a while to understand how decorators work in Python and when are they useful. And even after I understood them, I still had to look up how to do them properly (for example how to make a decorator with parameters).
Then a I saw this paragraph in the official documentation:
A function definition may be wrapped by one or more decorator expressions. Decorator expressions are evaluated when the function is defined, in the scope that contains the function definition. The result must be a callable, which is invoked with the function object as the only argument. The returned value is bound to the function name instead of the function object. Multiple decorators are applied in nested fashion.
I have not found any other explanation of decorators anywhere else in the docs. Because there is nothing more to explain!
All you need to know is that your @expression has to return a
callable which will be called with the wrapped function as an
argument, and result will be bound to the function name. And
that’s it.
A simple decorator might look something like this:
def logs(func):
def wrapper(*args, **kwargs):
logger.info("Start")
funs(*args, **kwargs)
logger.info("Stop")
return wrapper
@logs # Return the wrapper directly
def greeter(name):
print(f"Hello {name}")Need to pass arguments to the wrapper?
def repeated(times):
def decorator(func):
def wrapper(*args, **kwargs):
for i in range(times):
func(*args, **kwargs)
return wrapper
return decorator
@repeated(3) # Call `repeated` to get the wrapper
def printer(message):
print(message)The lesson is: read the documentation, it’s all there. I know I didn’t…