Contents
What are Lisp macros?
The Common Lisp macro facility allows the user to define arbitrary functions that convert certain Lisp forms into different forms before evaluating or compiling them. This is done at the expression level, not at the character-string level as in most other languages.
What are Lisp macros good for?
Common Lisp allows you to write macros that do whatever source transformation you want. Scheme gives you a hygienic pattern-matching system that lets you perform transformations as well.
How do you pass arguments to decorators in Python?
Decorators with parameters in Python
- Function can be assigned to a variable i.e they can be referenced.
- Function can be passed as an argument to another function.
- Function can be returned from a function.
Where are Python decorators used?
Decorators are used for anything that you want to transparently “wrap” with additional functionality. Django uses them for wrapping “login required” functionality on view functions, as well as for registering filter functions. You can use class decorators for adding named logs to classes.
What do Python decorators do?
A decorator is a design pattern in Python that allows a user to add new functionality to an existing object without modifying its structure. Decorators are usually called before the definition of a function you want to decorate.
How are decorators similar to macros in Lisp?
Many other languages have incorporated macros, but without knowing much about it I will go out on a limb and say that Python decorators are similar to Lisp macros in power and possibility. I think it’s safe to say that the goal of macros in a language is to provide a way to modify elements of the language.
Can you use decorators to implement macros in Python?
Indeed, you can use Python decorators to implement the Decorator pattern, but that’s an extremely limited use of it. Python decorators, I think, are best equated to macros.
Why are decorators a big deal in Python?
The reason I think decorators will have such a big impact is because this little bit of syntax sugar changes the way you think about programming. Indeed, it brings the idea of “applying code to other code” (i.e.: macros) into mainstream thinking by formalizing it as a language construct.
What is the return value of a decorator function in Python?
The return value of the decorator function must be a function used to wrap the function to be decorated. That is, Python will take the returned function and call it at decoration time, passing the function to be decorated. That’s why we have three levels of functions; the inner one is the actual replacement function.