Define a better public API about ethereumjs-abi

[axic]

cc @tinybike @wanderer

[wanderer]

I like the simplicity of raw(De|En)code. I think exposing both would be a good idea. For encode wouldn't parsing the JSON abi be easier to do than a string?

[axic]

The ABI JSON makes it easy to support overloading for encoding, e.g. if the ABI defines someMethod with both bytes and uint as an input, encode() could decide which one to encode based on the type of arguments passed in Javascript. However this is not the case in decode() where the type needs to be given explicitly. This limits the usefulness of the JSON to encoding only.

Based on this, I think the JSON part would only make sense the way it is done in web3 - to instantiate objects which proxy encoding/decoding to the destination via RPC.

I like this shorthand though for both encoding and decoding: encode('someMethod(bytes,uint)', <bytes data>, 1234). Perhaps for decode() it should support the expected return type as: decode('someMethod(bytes,uint):(boolean)')

rawEncode() and rawDecode() shall remain unchanged.

[holgerd77]

This probably needs further discussion if wished to be pursued.