Limitations

This is a list of known limitations. If you really want to see any of these, or other features please raise an issue and describe your use case.

Type Hinting

Variadic Generics

C# does not have a notion of Tuple<T...>, so the type annotation using Tuple[*T] in Python cannot be statically converted into a C#.NET type. See PEP646 for more details and 25.

Union Types

Python's type hinting supports Union types, which are not supported in C#.NET. This includes both typing.Union and the union operator described in PEP 604.

Classes

CSnakes does not support source generation for custom types, this includes dataclasses and named tuple instances.

Functions which return class instances will return a PyObject in C#.NET which you can use to pass into other functions. This type is a reference to the return value.

def create_person(name: str, age: int) -> Person:
    return Person(name, age)

CSnakes will create a method signature like this:

public PyObject CreatePerson(string name, long age);

There are some public methods on the PyObject class that you can use to interact with the object, such as GetAttr and Call. Any PyObject has a ToString() method that will return the string representation of the object, but you cannot convert the instance to a specific CLR type.

var person = module.CreatePerson("Alice", 42);
var name = person.GetAttr("name");
var age = person.GetAttr("age");

Native AOT

When using Native AOT compilation, only the source generated bindings approach is supported. The manual Python binding method described in Manual Integration is not compatible with Native AOT.

This limitation exists because casting Python objects to .NET containers like Tuple, Dictionary, List, or Coroutine requires reflection when done dynamically, which is not supported in Native AOT compilation. The source generator solves this by generating compiled bindings and reflection code at build time without using System.Reflection, making the generated code AOT-ready.

See the Native AOT Support section for complete details on requirements and configuration.