I ended up playing around with decorators and decided to document what I figured out for anyone who wants to take advantage of this before any documentation comes out. Please feel free to edit this if you see any mistakes. General Points Decorators are called when the class is declared—not when an object is instantiated. … Read more
Starting from Python 3.2 there is a built-in decorator: @functools.lru_cache(maxsize=100, typed=False) Decorator to wrap a function with a memoizing callable that saves up to the maxsize most recent calls. It can save time when an expensive or I/O bound function is periodically called with the same arguments. Example of an LRU cache for computing Fibonacci … Read more
The @ symbol is in fact a JavaScript expression currently proposed to signify decorators: Decorators make it possible to annotate and modify classes and properties at design time. Here’s an example of setting up Redux without and with a decorator: Without a decorator import React from ‘react’; import * as actionCreators from ‘./actionCreators’; import { … Read more
Take a look at the inspect module – this will do the inspection of the various code object properties for you. >>> inspect.getfullargspec(a_method) ([‘arg1’, ‘arg2’], None, None, None) The other results are the name of the *args and **kwargs variables, and the defaults provided. ie. >>> def foo(a, b, c=4, *arglist, **keywords): pass >>> inspect.getfullargspec(foo) … Read more
I use decorators mainly for timing purposes def time_dec(func): def wrapper(*arg): t = time.clock() res = func(*arg) print func.func_name, time.clock()-t return res return wrapper @time_dec def myFunction(n): …
Proxy, Decorator, Adapter, and Bridge are all variations on “wrapping” a class. But their uses are different. Proxy could be used when you want to lazy-instantiate an object, or hide the fact that you’re calling a remote service, or control access to the object. Decorator is also called “Smart Proxy.” This is used when you … Read more
I’ve to add the following in the settings.json file of vscode to remove the warning. “javascript.implicitProjectConfig.experimentalDecorators”: true VSCode -> Preferences -> Settings UPDATE As Clepsyd pointed out, this setting had been deprecated. You need to use now “js/ts.implicitProjectConfig.experimentalDecorators”:true
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 I mean is: def decorator_factory(argument): def decorator(function): def wrapper(*args, **kwargs): funny_stuff() something_with_argument(argument) result = … Read more
When you use a decorator, you’re replacing one function with another. In other words, if you have a decorator def logged(func): def with_logging(*args, **kwargs): print(func.__name__ + ” was called”) return func(*args, **kwargs) return with_logging then when you say @logged def f(x): “””does some math””” return x + x * x it’s exactly the same as … Read more
The property() function returns a special descriptor object: >>> property() <property object at 0x10ff07940> It is this object that has extra methods: >>> property().getter <built-in method getter of property object at 0x10ff07998> >>> property().setter <built-in method setter of property object at 0x10ff07940> >>> property().deleter <built-in method deleter of property object at 0x10ff07998> These act as … Read more