Just subclass the type >>> class X(str): … def my_method(self): … return int(self) … >>> s = X(“Hi Mom”) >>> s.lower() ‘hi mom’ >>> s.my_method() Traceback (most recent call last): File “<stdin>”, line 1, in <module> File “<stdin>”, line 3, in my_method ValueError: invalid literal for int() with base 10: ‘Hi Mom’ >>> z = … Read more
You can define a new class in your application at lib/ext/string.rb and put this content in it: class String def to_magic “magic” end end To load this class, you will need to require it in your config/application.rb file or in an initializer. If you had many of these extensions, an initializer is better! The way … Read more
Edit: See the second code option below (it is tested and works). The first one has some limitations. Since you can’t modify any of those functions, it appears you have to go after the XMLHttpRequest prototype. Here’s one idea (untested, but you can see the direction): (function() { var open = XMLHttpRequest.prototype.open; XMLHttpRequest.prototype.open = function(method, … Read more
put the file monkey_patching.py in any of your apps and import it in app’s __init__.py file. ie: app/monkey_patching.py #app/monkey_patching.py from django.contrib.auth.models import User User.add_to_class(‘openid’, models.CharField(max_length=250,blank=True)) def get_user_name(self): if self.first_name or self.last_name: return self.first_name + ” ” + self.last_name return self.username User.add_to_class(“get_user_name”,get_user_name) app/__init__.py #app/__init__.py import monkey_patching
Monkey Patching What you want to do is called monkey patching — you mutate a built-in prototype. There are many wrong ways to do it, and it should be avoided entirely, because it has negative Web compatibility impacts. I will, however, demonstrate how this can be done in a way that matches existing prototype features most closely. … Read more
In Python, there is a difference between functions and bound methods. >>> def foo(): … print “foo” … >>> class A: … def bar( self ): … print “bar” … >>> a = A() >>> foo <function foo at 0x00A98D70> >>> a.bar <bound method A.bar of <__main__.A instance at 0x00A9BC88>> >>> Bound methods have been … Read more
Yes, you can replace an inner function, even if it is using a closure. You’ll have to jump through a few hoops though. Please take into account: You need to create the replacement function as a nested function too, to ensure that Python creates the same closure. If the original function has a closure over … Read more
It may help to think of how Python namespaces work: they’re essentially dictionaries. So when you do this: from a_package.baz import do_something_expensive do_something_expensive = lambda: ‘Something really cheap.’ think of it like this: do_something_expensive = a_package.baz[‘do_something_expensive’] do_something_expensive = lambda: ‘Something really cheap.’ Hopefully you can realize why this doesn’t work then 🙂 Once you import … Read more
The following should work: import thirdpartymodule_a import thirdpartymodule_b def new_init(self): self.a = 43 thirdpartymodule_a.SomeClass.__init__ = new_init thirdpartymodule_b.dosomething() If you want the new init to call the old init replace the new_init() definition with the following: old_init = thirdpartymodule_a.SomeClass.__init__ def new_init(self, *k, **kw): old_init(self, *k, **kw) self.a = 43
The best explanation I heard for Monkey patching/Duck-punching is by Patrick Ewing in RailsConf 2007 …if it walks like a duck and talks like a duck, it’s a duck, right? So if this duck is not giving you the noise that you want, you’ve got to just punch that duck until it returns what you … Read more