Passing a trait as a parameter to `Dict`?

This is related to a proposal for adding Middleware functionality to Lightbug HTTP: https://github.com/saviorand/lightbug_http/pull/33#issuecomment-2105547981
We're trying to do something like the following:

## HTTPHandler is an interface for handling HTTP requests in the RouterMiddleware.
## It is a leaf node in the middleware chain.
trait HTTPHandler:
    fn handle(self, context: Context) -> HTTPResponse:
        ...

## Router middleware routes requests to different middleware based on the path.
@value
struct RouterMiddleware(Middleware):
    var next: Middleware
    var routes: Dict[String, HTTPHandler]

## HTTPHandler is an interface for handling HTTP requests in the RouterMiddleware.
## It is a leaf node in the middleware chain.
trait HTTPHandler:
    fn handle(self, context: Context) -> HTTPResponse:
        ...

## Router middleware routes requests to different middleware based on the path.
@value
struct RouterMiddleware(Middleware):
    var next: Middleware
    var routes: Dict[String, HTTPHandler]

## HTTPHandler is an interface for handling HTTP requests in the RouterMiddleware.
## It is a leaf node in the middleware chain.
trait HTTPHandler:
    fn handle(self, context: Context) -> HTTPResponse:
        ...

## Router middleware routes requests to different middleware based on the path.
@value
struct RouterMiddleware(Middleware):
    var next: Middleware
    var routes: Dict[String, HTTPHandler]

## HTTPHandler is an interface for handling HTTP requests in the RouterMiddleware.
## It is a leaf node in the middleware chain.
trait HTTPHandler:
    fn handle(self, context: Context) -> HTTPResponse:
        ...

## Router middleware routes requests to different middleware based on the path.
@value
struct RouterMiddleware(Middleware):
    var next: Middleware
    var routes: Dict[String, HTTPHandler]

Where

routes: Dict[String, HTTPHandler]

routes: Dict[String, HTTPHandler]

routes: Dict[String, HTTPHandler]

routes: Dict[String, HTTPHandler] takes in an

HTTPHandler

HTTPHandler

HTTPHandler

HTTPHandler trait which can be implemented by different handlers, including ones created by the user.
Currently, since

Dict

Dict

Dict

Dict expects a value that implements

CollectionElement

CollectionElement

CollectionElement

CollectionElement, so we're getting the following error:

middleware/router.mojo:15:36: error: 'Dict' parameter #1 has 'CollectionElement' type, but value has type 'AnyTrait[HTTPHandler]'
        self.routes = Dict[String, HTTPHandler]()

middleware/router.mojo:15:36: error: 'Dict' parameter #1 has 'CollectionElement' type, but value has type 'AnyTrait[HTTPHandler]'
        self.routes = Dict[String, HTTPHandler]()

middleware/router.mojo:15:36: error: 'Dict' parameter #1 has 'CollectionElement' type, but value has type 'AnyTrait[HTTPHandler]'
        self.routes = Dict[String, HTTPHandler]()

middleware/router.mojo:15:36: error: 'Dict' parameter #1 has 'CollectionElement' type, but value has type 'AnyTrait[HTTPHandler]'
        self.routes = Dict[String, HTTPHandler]()

This persists even if

HTTPHandler

HTTPHandler

HTTPHandler

HTTPHandler extends

CollectionElement

CollectionElement

CollectionElement

CollectionElement like so:

trait HTTPHandler(CollectionElement)

trait HTTPHandler(CollectionElement)

trait HTTPHandler(CollectionElement)

trait HTTPHandler(CollectionElement).

Any ideas on how we can get this to work?

GitHub

Propose Middleware Solution by drujensen · Pull Request #33 · savio...

This is a proposal and code sample for adding middleware to the light bug project.
Proposal
The chain of responsibility design pattern is used to chain together pieces of middleware that will each ...

Passing a trait as a parameter to `Dict`?

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