Monkey-patch Python class
import module class ReplaceClass(object): …. module.MyClass = ReplaceClass
monkeypatching
Is it possible to replace (monkeypatch) PHP functions?
This is a bit late, but I just want to point out that since PHP 5.3, it is actually possible to override internal functions without using a PHP extension. The trick is that you can redefine an internal PHP function inside a namespace. It’s based on the way PHP does name resolution for functions: Inside … Read more
Patch routine call in delphi
I use the following code: procedure PatchCode(Address: Pointer; const NewCode; Size: Integer); var OldProtect: DWORD; begin if VirtualProtect(Address, Size, PAGE_EXECUTE_READWRITE, OldProtect) then begin Move(NewCode, Address^, Size); FlushInstructionCache(GetCurrentProcess, Address, Size); VirtualProtect(Address, Size, OldProtect, @OldProtect); end; end; type PInstruction = ^TInstruction; TInstruction = packed record Opcode: Byte; Offset: Integer; end; procedure RedirectProcedure(OldAddress, NewAddress: Pointer); var NewCode: TInstruction; … Read more
Can I patch a Python decorator before it wraps a function?
It should be noted that several of the answers here will patch the decorator for the entire test session rather than a single test instance; which may be undesirable. Here’s how to patch a decorator that only persists through a single test. Our unit to be tested with the undesired decorator: # app/uut.py from app.decorators … Read more
Why is it frowned upon to modify JavaScript object’s prototypes?
The problem is that prototype can be modified in several places. For example one library will add map method to Array’s prototype and your own code will add the same but with another purpose. So one implementation will be broken.
Can you monkey patch methods on core types in Python?
No, you cannot. In Python, all data (classes, methods, functions, etc) defined in C extension modules (including builtins) are immutable. This is because C modules are shared between multiple interpreters in the same process, so monkeypatching them would also affect unrelated interpreters in the same process. (Multiple interpreters in the same process are possible through … Read more
Can I add custom methods/attributes to built-in Python types?
You can’t directly add the method to the original type. However, you can subclass the type then substitute it in the built-in/global namespace, which achieves most of the effect desired. Unfortunately, objects created by literal syntax will continue to be of the vanilla type and won’t have your new methods/attributes. Here’s what it looks like … Read more
Making object JSON serializable with regular encoder
As I said in a comment to your question, after looking at the json module’s source code, it does not appear to lend itself to doing what you want. However the goal could be achieved by what is known as monkey-patching (see question What is a monkey patch?). This could be done in your package’s … Read more
How to add property to a class dynamically?
I suppose I should expand this answer, now that I’m older and wiser and know what’s going on. Better late than never. You can add a property to a class dynamically. But that’s the catch: you have to add it to the class. >>> class Foo(object): … pass … >>> foo = Foo() >>> foo.a … Read more
When monkey patching an instance method, can you call the overridden method from the new implementation?
EDIT: It has been 9 years since I originally wrote this answer, and it deserves some cosmetic surgery to keep it current. You can see the last version before the edit here. You can’t call the overwritten method by name or keyword. That’s one of the many reasons why monkey patching should be avoided and … Read more