decorator

问题 I was trying to use Python decorator to catch exceptions and log the exceptions. import os.path import shutil class log(object): def __init__(self, f): print "Inside __init__()" self.f = f def __call__(self, *args): print "Inside __call__()" try: self.f(*args) except Exception: print "Sorry" @log def testit(a, b, c): print a,b,c raise RuntimeError() if __name__ == "__main__": testit(1,2,3) It works fine Desktop> python deco.py Inside __init__() Inside __call__() 1 2 3 Sorry The issue is that

问题 I wanted to use a decorator to handle exceptions in my PyQt5 application: def handle_exceptions(func): def func_wrapper(*args, **kwargs): try: print(args) return func(*args, **kwargs) except Exception as e: print(e) return None return func_wrapper class MainWindow(QMainWindow): def __init__(self): QMainWindow.__init__(self) loadUi("main_window.ui",self) self.connect_signals() def connect_signals(self): self.menu_action.triggered.connect(self.fun) @handle_exceptions def fun(self): print("hello

问题 I'm a newbie to google app engine. I want the security restriction for url of cron so that it shouldn't be accessible by url directly. For this I've already read the docs and some of Q&As ([Google app engine: security of cron jobs). I implemented the login : admin solution suggested in this link. But I failed to implement security as self.request.headers.get('X-AppEngine-Cron') is always None , whether it is cron or accessed via url directly. So I don't know from where is the request coming

问题 I've got a class which contains a number of lists where whenever something is added to one of the lists, I need to trigger a change to the instance's state. I've created a simple demonstration class below to try to demonstrate what I'm trying to do. Suppose I have a class like this: class MyClass: added = False def _decorator(self, f): def func(item): added = true return f(item) return func def __init__(self): self.list = [1, 2, 3] self.list.append = self._decorator(self.list.append) Since a

问题 This answer almost describes the first half of the question. It says: After reading the Gang of Four definitions, I'm not convinced there's a real difference. (included for convenience) Decorator: Allows for the dynamic wrapping of objects in order to modify their existing responsibilities and behaviours Chain of Responsibility: Gives more than one object an opportunity to handle a request by linking receiving objects together Wikipedia fleshes them out a little, but some of it's kinda

问题 Just tried to use decorators in React: import React from 'react'; import Fade from './Transitions/Fade' import withVisible from './withVisible' @withVisible() const App = props => <Fade visible={props.visible} duration={500}> Hello </Fade> export default App If I use the common way ( withVisible()(App) ) then it's working properly. (My guess is that NodeJS can't compile my code with the @ ) [Syntax error: Unexpected token (@) ] import React from 'react' const withVisible = () => Component =>

问题 In the below code snippet, two objects named div are created at lines 1 and 2. How does python differentiate between the two div objects created under the same scope? When id() is applied on both objects, two different addresses are shown for the similar named objects. Why is this so? def div(a,b): return a/b print(id(div)) # id = 199......1640 ################################ line 1 def smart_div(func): def inner(a,b): if a<b: a,b=b,a return func(a,b) return inner a = int(input("Enter 1st: "

问题 In the below code snippet, two objects named div are created at lines 1 and 2. How does python differentiate between the two div objects created under the same scope? When id() is applied on both objects, two different addresses are shown for the similar named objects. Why is this so? def div(a,b): return a/b print(id(div)) # id = 199......1640 ################################ line 1 def smart_div(func): def inner(a,b): if a<b: a,b=b,a return func(a,b) return inner a = int(input("Enter 1st: "

问题 I'm using a Decorator (class) in an Instance method of another class, like this: class decorator_with_arguments(object): def __init__(self, arg1=0, arg2=0, arg3=0): self.arg1 = arg1 self.arg2 = arg2 self.arg3 = arg3 def __call__(self, f): print("Inside __call__()") def wrapped_f(*args): print(f.__qualname__) f(*args) return wrapped_f class Lol: @decorator_with_arguments("hello") def sayHello(self,a1, a2, a3, a4): print(self.sayHello.__qualname__) Now, when I print out self.sayHello.__qualname

问题 So, I'm pretty familiar with wrapping functions in views.py. So I've written a decorator to redirect to the default REDIRECT_URL if the user is logged in (sort of a reverse login_required ); it's based on how I've made views in the past: def not_logged_in(redirect_url=None, redirect_field_name=REDIRECT_FIELD_NAME): def decorator(view_func, *args, **kwargs): def wrapper(request, *args, **kwargs): if not request.user.is_authenticated(): return view_func(*args, **kwargs) else: redirect_url =