accounts/abi/bind/backends: remove nil and remote backends

The remote backend is superseded by ethclient.

The nil backend's stated purpose was to enable testing of
accounts/abi/bind. None of its methods actually worked. A much simpler
way to get a crashing backend is to simply pass nil as the backend. With
a one-line change to the generator (removing two explicit interface
assertions), passing nil actually works.

Removing these backends means that less changes are required later.

accounts/abi/bind/backends/nil.go

-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package backends
-
-import (
-	"math/big"
-
-	"github.com/ethereum/go-ethereum/accounts/abi/bind"
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/types"
-	"golang.org/x/net/context"
-)
-
-// This nil assignment ensures compile time that nilBackend implements bind.ContractBackend.
-var _ bind.ContractBackend = (*nilBackend)(nil)
-
-// nilBackend implements bind.ContractBackend, but panics on any method call.
-// Its sole purpose is to support the binding tests to construct the generated
-// wrappers without calling any methods on them.
-type nilBackend struct{}
-
-func (*nilBackend) ContractCall(context.Context, common.Address, []byte, bool) ([]byte, error) {
-	panic("not implemented")
-}
-func (*nilBackend) EstimateGasLimit(context.Context, common.Address, *common.Address, *big.Int, []byte) (*big.Int, error) {
-	panic("not implemented")
-}
-func (*nilBackend) HasCode(context.Context, common.Address, bool) (bool, error) {
-	panic("not implemented")
-}
-func (*nilBackend) SuggestGasPrice(context.Context) (*big.Int, error) { panic("not implemented") }
-func (*nilBackend) PendingAccountNonce(context.Context, common.Address) (uint64, error) {
-	panic("not implemented")
-}
-func (*nilBackend) SendTransaction(context.Context, *types.Transaction) error {
-	panic("not implemented")
-}
-
-// NewNilBackend creates a new binding backend that can be used for instantiation
-// but will panic on any invocation. Its sole purpose is to help testing.
-func NewNilBackend() bind.ContractBackend {
-	return new(nilBackend)
-}

accounts/abi/bind/backends/remote.go

-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package backends
-
-import (
-	"math/big"
-
-	"github.com/ethereum/go-ethereum/accounts/abi/bind"
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/types"
-	"github.com/ethereum/go-ethereum/rlp"
-	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
-)
-
-// This nil assignment ensures compile time that rpcBackend implements bind.ContractBackend.
-var _ bind.ContractBackend = (*rpcBackend)(nil)
-
-// rpcBackend implements bind.ContractBackend, and acts as the data provider to
-// Ethereum contracts bound to Go structs. It uses an RPC connection to delegate
-// all its functionality.
-type rpcBackend struct {
-	client *rpc.Client // RPC client connection to interact with an API server
-}
-
-// NewRPCBackend creates a new binding backend to an RPC provider that can be
-// used to interact with remote contracts.
-func NewRPCBackend(client *rpc.Client) bind.ContractBackend {
-	return &rpcBackend{client: client}
-}
-
-// HasCode implements ContractVerifier.HasCode by retrieving any code associated
-// with the contract from the remote node, and checking its size.
-func (b *rpcBackend) HasCode(ctx context.Context, contract common.Address, pending bool) (bool, error) {
-	block := "latest"
-	if pending {
-		block = "pending"
-	}
-	var hex string
-	err := b.client.CallContext(ctx, &hex, "eth_getCode", contract, block)
-	if err != nil {
-		return false, err
-	}
-	return len(common.FromHex(hex)) > 0, nil
-}
-
-// ContractCall implements ContractCaller.ContractCall, delegating the execution of
-// a contract call to the remote node, returning the reply to for local processing.
-func (b *rpcBackend) ContractCall(ctx context.Context, contract common.Address, data []byte, pending bool) ([]byte, error) {
-	args := struct {
-		To   common.Address `json:"to"`
-		Data string         `json:"data"`
-	}{
-		To:   contract,
-		Data: common.ToHex(data),
-	}
-	block := "latest"
-	if pending {
-		block = "pending"
-	}
-	var hex string
-	err := b.client.CallContext(ctx, &hex, "eth_call", args, block)
-	if err != nil {
-		return nil, err
-	}
-	return common.FromHex(hex), nil
-
-}
-
-// PendingAccountNonce implements ContractTransactor.PendingAccountNonce, delegating
-// the current account nonce retrieval to the remote node.
-func (b *rpcBackend) PendingAccountNonce(ctx context.Context, account common.Address) (uint64, error) {
-	var hex rpc.HexNumber
-	err := b.client.CallContext(ctx, &hex, "eth_getTransactionCount", account.Hex(), "pending")
-	if err != nil {
-		return 0, err
-	}
-	return hex.Uint64(), nil
-}
-
-// SuggestGasPrice implements ContractTransactor.SuggestGasPrice, delegating the
-// gas price oracle request to the remote node.
-func (b *rpcBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
-	var hex rpc.HexNumber
-	if err := b.client.CallContext(ctx, &hex, "eth_gasPrice"); err != nil {
-		return nil, err
-	}
-	return (*big.Int)(&hex), nil
-}
-
-// EstimateGasLimit implements ContractTransactor.EstimateGasLimit, delegating
-// the gas estimation to the remote node.
-func (b *rpcBackend) EstimateGasLimit(ctx context.Context, sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
-	args := struct {
-		From  common.Address  `json:"from"`
-		To    *common.Address `json:"to"`
-		Value *rpc.HexNumber  `json:"value"`
-		Data  string          `json:"data"`
-	}{
-		From:  sender,
-		To:    contract,
-		Data:  common.ToHex(data),
-		Value: rpc.NewHexNumber(value),
-	}
-	// Execute the RPC call and retrieve the response
-	var hex rpc.HexNumber
-	err := b.client.CallContext(ctx, &hex, "eth_estimateGas", args)
-	if err != nil {
-		return nil, err
-	}
-	return (*big.Int)(&hex), nil
-}
-
-// SendTransaction implements ContractTransactor.SendTransaction, delegating the
-// raw transaction injection to the remote node.
-func (b *rpcBackend) SendTransaction(ctx context.Context, tx *types.Transaction) error {
-	data, err := rlp.EncodeToBytes(tx)
-	if err != nil {
-		return err
-	}
-	return b.client.CallContext(ctx, nil, "eth_sendRawTransaction", common.ToHex(data))
-}

accounts/abi/bind/template.go

@@ -127,7 +127,7 @@ package {{.Package}}
 
 	// New{{.Type}} creates a new instance of {{.Type}}, bound to a specific deployed contract.
 	func New{{.Type}}(address common.Address, backend bind.ContractBackend) (*{{.Type}}, error) {
-	  contract, err := bind{{.Type}}(address, backend.(bind.ContractCaller), backend.(bind.ContractTransactor))
+	  contract, err := bind{{.Type}}(address, backend, backend)
 	  if err != nil {
 	    return nil, err
 	  }