torch.jit.interface

torch.jit.interface(obj)

This decorator can be used to define an interface that can be used to annotate classes or modules of different types. This can be used for to annotate a submodule or attribute class that could have different types that implement the same interface, or which could be swapped at runtime; or to store a list of modules or classes of varying types.

It is sometimes used to implement “Callables” - functions or modules that implement an interface but whose implementations differ and which can be swapped out.

Example:

import torch
from typing import List

@torch.jit.interface
class InterfaceType:
    def run(self, x: torch.Tensor) -> torch.Tensor:
        pass

# implements InterfaceType
@torch.jit.script
class Impl1:
    def run(self, x: torch.Tensor) -> torch.Tensor:
        return x.relu()

class Impl2(torch.nn.Module):
    def __init__(self):
        super().__init__()
        self.val = torch.rand(())

    @torch.jit.export
    def run(self, x: torch.Tensor) -> torch.Tensor:
        return x + self.val

def user_fn(impls: List[InterfaceType], idx: int, val: torch.Tensor) -> torch.Tensor:
    return impls[idx].run(val)

user_fn_jit = torch.jit.script(user_fn)

impls = [Impl1(), torch.jit.script(Impl2())]
val = torch.rand(4, 4)
user_fn_jit(impls, 0, val)
user_fn_jit(impls, 1, val)