Move filter method to use Method class

[kclowes]

What was wrong?

Filter is the last method in Eth that wasn't using Method. This PR fixes that.

Todo:

• Add entry to the release notes
• Make sure tests are using the correct middleware
• Better solution than passing around a string in place of a method
• Lint
• Get rid of TODOs
• Manually test

Cute Animal Picture

[kclowes]

@pipermerriam I can't figure out how to pull this out without going back to passing around a string method name, since all of the formatters are chosen based on the method name. Let me know if you see another way!

[pipermerriam]

If we can't get this out, lets consider making it generic. I'd suggest doing that as a follow up to this PR.

Roughly speaking, it looks like we need an official way for a Method to short-circut the JSON-RPC request and to return a value that is generated locally. That could be using something like an exception like we did here, but I think that's probably not the best choice here because it feels like a heavy way to implement what is effectively an if/else.

We might need to return something more structured from process_params that we can then switch on.

request = method.preprocess_request(module, *args, **kwargs)
if request.is_json_rpc:
    ...  # do the actual request
elif request.has_static_response:
    ...  # directly return the response value.
else:
    ...  # dunno, maybe just raise Exception("Invariant")

I don't know if this is going to work, or be clean. Just my stab at what the API could look like. I think you'll be doing yourself and everyone on the team a favor to spend some time working on these APIs, especially in making them less cryptic in how they work.

[kclowes]

Yeah, agreed. I'll do some mucking around with it in another PR.

[kclowes]

I think this is ready for a final look @marcgarreau and @pipermerriam!

[pipermerriam]

If we can't get this out, lets consider making it generic. I'd suggest doing that as a follow up to this PR.

Roughly speaking, it looks like we need an official way for a Method to short-circut the JSON-RPC request and to return a value that is generated locally. That could be using something like an exception like we did here, but I think that's probably not the best choice here because it feels like a heavy way to implement what is effectively an if/else.

We might need to return something more structured from process_params that we can then switch on.

request = method.preprocess_request(module, *args, **kwargs)
if request.is_json_rpc:
    ...  # do the actual request
elif request.has_static_response:
    ...  # directly return the response value.
else:
    ...  # dunno, maybe just raise Exception("Invariant")

I don't know if this is going to work, or be clean. Just my stab at what the API could look like. I think you'll be doing yourself and everyone on the team a favor to spend some time working on these APIs, especially in making them less cryptic in how they work.