Can you write a decorator that accepts an argument?

Can you write a decorator that accepts an argument?

decorator_with_args is a function which accepts a custom argument and which returns the actual decorator (that will be applied to the decorated function). One effect of decorating a function is that the name foo is overridden upon decorator declaration.

How do decorators pass arguments?

Use a decorator factory function to pass parameters to a decorator

1. state = dict()
2. def decorator_factory(active, *args, **kwargs):
3. def decorator(func):
4. print(“running decorator_factory(active=%s) -> decorator(%s)” % (active, func))
5. if active:
6. state. update({str(func): “active”})
7. else:
8. state.

What is a Python decorator?

A decorator in Python is a function that takes another function as its argument, and returns yet another function. Decorators can be extremely useful as they allow the extension of an existing function, without any modification to the original function source code.

Why do we use decorators?

Decorators are very powerful and useful tool in Python since it allows programmers to modify the behavior of function or class. Decorators allow us to wrap another function in order to extend the behavior of the wrapped function, without permanently modifying it.

What are decorators in flask?

A decorator is a function that wraps and replaces another function. Since the original function is replaced, you need to remember to copy the original function’s information to the new function. Use functools. wraps() to handle this for you.

Is Python written in Java?

To support this type of development, a Python implementation written in Java is under development, which allows calling Python code from Java and vice versa. In this implementation, Python source code is translated to Java bytecode (with help from a run-time library to support Python’s dynamic semantics).

Why do we need decorators in Python?

Decorators dynamically alter the functionality of a function, method, or class without having to directly use subclasses or change the source code of the function being decorated. Using decorators in Python also ensures that your code is DRY(Don’t Repeat Yourself).

Should you use Python decorators?

Python’s decorators allow you to extend and modify the behavior of a callable (functions, methods, and classes) without permanently modifying the callable itself. Any sufficiently generic functionality you can “tack on” to an existing class or function’s behavior makes a great use case for decoration.

Can decorators be chained?

Chaining decorators means applying more than one decorator inside a function. Python allows us to implement more than one decorator to a function. It makes decorators useful for resuabale building blocks as it accumulates the several effects together. It is also knows as nested decorators in Python.

How are decorators with arguments different from normal decorators?

The syntax for decorators with arguments is a bit different – the decorator with arguments should return a function that will take a function and return another function. So it should really return a normal decorator. A bit confusing, right?

What to do with Decorators with arguments in Python?

Anyway, the syntax for decorators with arguments is a bit different – the decorator with arguments should return a function that will take a function and return another function. So it should really return a normal decorator.

Can a decorator be applied to a function?

As a decorator is a function, it actually works as a regular decorator with arguments: This can be applied to a regular decorator in order to add parameters. So for instance, say we have the decorator which doubles the result of a function:

Do you need a wrapper for a decorator?

The solution proposed by t.dubrownik shows a pattern which is always the same: you need the three-layered wrapper regardless of what the decorator does. So I thought this is a job for a meta-decorator, that is, a decorator for decorators. As a decorator is a function, it actually works as a regular decorator with arguments: