I use it quite a lot (having made it), most often when I need to recursively process complex heterogeneous data structures. Merging two data structures, treemap

I use it quite a lot (having made it), most often when I need to recursively process complex heterogeneous data structures. Merging two data structures, treemap, processing a Python AST, etc. Also in any situation where you want to be able to register new behavior. One case where I'm finding it extremely useful is that I'm currently using ovld to implement a serialization library (https://github.com/breuleux/serieux https://github.com/breuleux/serieux, but I haven't documented anything yet). The arguments for deserialization are (declared_type, value, context). With multimethods, I can define * deserialize(type[int], str, Any) to deserialize a string into an int * deserialize(type[str], Regexp[r"^\$"], Environment) to deserialize $XYZ as an environment variable lookup but only if the context has the Environment type * deserialize(type[Any], Path, WorkingDirectory) to deserialize from a file That's one situation where ovld's performance and codegen capabilities come in handy: the overhead is low enough to remain in the same performance ballpark as Pydantic v2.