Alternative implementation

[dalf]

See searxng/searxng#2981

The documentation is not updated, but the example works:

• if the code calls install_botdetection(app, redis, ...), the botdetection works as expected
• if the code does not call this function, the botdetection is fully disabled (no endpoint for the token, no overhead, nothing).

[return42]

Just a hint / the naming is a bit misleading: A RouteFilter is a (is of type) RequestFilter while a PredefinedRequestFilter is a list (a enumeration type) of functions (with identical prototype and return type).

• PredefinedRequestFilter --> FilterMethods (or similar)

To avoid a conflict with searxng/searxng#3462 we should not change it here in this branch / we can do it later / just wanted to leaf a note while I'm in review of this PR.

---

The prototype of the filter methods in PredefinedRequestFilter is the same as the call function of the RequestFilter

IMO the inheritance RouteFilter(RequestFilter) is not valid / the call methods might have identical prototypes but a route filer is something complete different to a request filter: A RouteFilter is a map of URL routes to RequestFilters

This is not a specialization, the basket full of ducks is not the generalization of a duck.

[return42]

As described on Matrix: I work on the flask-middleware branch