python-decorators

i'm quite new with flask and i'm trying to use the migthy power of decorators :p I read lot of things and found tons of topics about python decorators here but nothing really helpful. @app.route('groups/<id_group>') @group_required(id_group) @login_required def groups_groupIndex(id_group): #do some stuff return render_template('index_group.html') This is the error i get : @group_required(id_group), NameError: name 'id_group' is not defined Ok, id_group is not defined yet, but I don't understand why i CAN use the id_group parameter from the URL in the function groups_groupIndex but NOT in the

In Flask I'm using a set of decorators for each route, but the code is "ugly": @app.route("/first") @auth.login_required @crossdomain(origin='*') @nocache def first_page: .... @app.route("/second") @auth.login_required @crossdomain(origin='*') @nocache def second_page: .... I would prefer to have a declaration that groups all of them with a single decorator: @nice_decorator("/first") def first_page: .... @nice_decorator("/second") def second_page: .... I tried to follow the answer at Can I combine two decorators into a single one in Python? but I cannot make it working: def composed(*decs):

While trying to figure out if a function is called with the @decorator syntax , we realized that inspect has a different behaviour when looking at a decorated class that inherits from a superclass. The following behaviour was found with CPython 3.6.2 under Windows 10. It was also reproduced in CPython 3.7.0 under Linux 64 bits. import inspect def decorate(f): lines = inspect.stack()[1].code_context print(f.__name__, lines) return f @decorate class Foo: pass @decorate class Bar(dict): pass Output Foo ['@decorate\n'] Bar ['class Bar(dict):\n'] Why does inheritance change the behaviour of inspect

I'm having a hard time understanding what happens when I try to nest descriptors/decorators. I'm using python 2.7. For example, let's take the following simplified versions of property and classmethod : class MyProperty(object): def __init__(self, fget): self.fget = fget def __get__(self, obj, objtype=None): print 'IN MyProperty.__get__' return self.fget(obj) class MyClassMethod(object): def __init__(self, f): self.f = f def __get__(self, obj, objtype=None): print 'IN MyClassMethod.__get__' def f(*args, **kwargs): return self.f(objtype, *args, **kwargs) return f Trying to nest them: class A

I'd like to use a decorator which accepts an argument, checks if that argument is not None, and if True it lets the decorated function run. I want to use this decorator inside a class definition, because I have a set of class methods which starts with checking if a specific class variable is None or not. I think it would look nicer if I used a decorator. I'd like to do something like this: # decorator def variable_tester(arg): def wrap(f): def wrapped_f(*args): if arg is not None: f(*args) else: pass return wrapped_f return wrap # class definition class my_class(object): def __init__(self):

I am trying to use click python package to pass a command line argument to a function. The example from official documentation works as explained. But nowhere in the documentation is it mentioned how to return a value back. None of the functions in the documentation returns a value, so I don't understand how to do this. Given example at documentation: import click @click.command() @click.option('--count', default=3, help='Number of greetings.') def hello(count): """Simple program that greets NAME for a total of COUNT times.""" for x in range(count): click.echo('Hello') if __name__ == '__main__