[ethapi] Expose overrides to eth client as well

[fxfactorial]

after seeing it mentioned in a tweet - checked and saw ethclient doesn't expose overrides of contract calls (eth_call)

also changed the extra pointer - maps are already pointers

[karalabe]

This is an internal packag,e you can't use it as an API surface, Go won't allow outside callers to access it. All in all internal is meant to be used internally by Geth.

[fxfactorial]

ahh - that's right - okay so I either move it out or make a same type in ethclient.go - i wonder if a type alias would do the trick here

[fxfactorial]

just tried - a type alias worked great - I make an account in outside go-ethereum code just fine

[karalabe]

The point of *map[common.Address]account is to differentiate between mandatory an optional arguments in the RPC layer. Please revert.

[fxfactorial]

but if caller doesn't provide the map - anyway it will be nil, no?

[fxfactorial]

ah - seems like i need to also change up abigen because my bindings now not compiling

[fjl]

We cannot change CallContract because it is part of the stable API, and many other projects use this API.

The state overrides are not supported everywhere, and I would strongly prefer to not add this functionality to ethclient. But I also understand it's annoying having to wrap the geth-specific APIs yourself.

I think what we could do is to add a new package "ethclient/gethclient" that contains an RPC wrapper for all the Geth-specific functionality.

[fxfactorial]

@fjl okay that's a good point - I agree. Is there an enumeration of the specific geth functionalities ?

[fjl]

Not really, but you can check the https://geth.ethereum.org/docs/rpc/server site for info about the geth-specific RPC methods (see sidebar).

[fxfactorial]

@fjl woof - that looks like quite a bit of refactoring to get that out the door - maybe if there is a design desired - i can impl that - otherwise i might go in a direction ya'll don't agree with

[fjl]

You don't need to add all the methods, just add the package and the method you want.
We can expand the method set later when more people want other methods.

If you need some design help, what I want is something that's basically like ethclient:

package gethclient

type Client struct{
     c *rpc.Client
}

type AccountOverrides struct{
	Nonce     *hexutil.Uint64              `json:"nonce"`
	Code      *hexutil.Bytes               `json:"code"`
	Balance   **hexutil.Big                `json:"balance"`
	State     *map[common.Hash]common.Hash `json:"state"`
	StateDiff *map[common.Hash]common.Hash `json:"stateDiff"`
}

func (ec *Client) Call(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int, overrides map[common.Address]AccountOverrides) ([]byte, error) {
    ...
}

[fjl]

I'm still interested to add this 'gethclient' package, but don't have time to work on it right now.
@fxfactorial If you have time, we would absolutely accept a PR to add a basic version of it, even if it only contains one method.

Closing this because we won't make the change in ethclient itself.