Make registerAssetProxy append only

packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol

@@ -32,43 +32,28 @@ contract MixinAssetProxyDispatcher is
     // Mapping from Asset Proxy Id's to their respective Asset Proxy
     mapping (bytes4 => IAssetProxy) public assetProxies;
 
-    /// @dev Registers an asset proxy to an asset proxy id.
-    ///      An id can only be assigned to a single proxy at a given time.
-    /// @param assetProxyId Id to register`newAssetProxy` under.
-    /// @param newAssetProxy Address of new asset proxy to register, or 0x0 to unset assetProxyId.
-    /// @param oldAssetProxy Existing asset proxy to overwrite, or 0x0 if assetProxyId is currently unused.
-    function registerAssetProxy(
-        bytes4 assetProxyId,
-        address newAssetProxy,
-        address oldAssetProxy
-    )
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
         external
         onlyOwner
     {
-        // Ensure the existing asset proxy is not unintentionally overwritten
+        IAssetProxy assetProxyContract = IAssetProxy(assetProxy);
+
+        // Ensure that no asset proxy exists with current id.
+        bytes4 assetProxyId = assetProxyContract.getProxyId();
         address currentAssetProxy = assetProxies[assetProxyId];
         require(
-            oldAssetProxy == currentAssetProxy,
-            "ASSET_PROXY_MISMATCH"
+            currentAssetProxy == address(0),
+            "ASSET_PROXY_ALREADY_EXISTS"
         );
 
-        IAssetProxy assetProxy = IAssetProxy(newAssetProxy);
-
-        // Ensure that the id of newAssetProxy matches the passed in assetProxyId, unless it is being reset to 0.
-        if (newAssetProxy != address(0)) {
-            bytes4 newAssetProxyId = assetProxy.getProxyId();
-            require(
-                newAssetProxyId == assetProxyId,
-                "ASSET_PROXY_ID_MISMATCH"
-            );
-        }
-
         // Add asset proxy and log registration.
-        assetProxies[assetProxyId] = assetProxy;
-        emit AssetProxySet(
+        assetProxies[assetProxyId] = assetProxyContract;
+        emit AssetProxyRegistered(
             assetProxyId,
-            newAssetProxy,
-            oldAssetProxy
+            assetProxy
         );
     }
 
@@ -112,7 +97,7 @@ contract MixinAssetProxyDispatcher is
                     0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
                 )
             }
-            IAssetProxy assetProxy = assetProxies[assetProxyId];
+            address assetProxy = assetProxies[assetProxyId];
 
             // Ensure that assetProxy exists
             require(

packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol

@@ -20,16 +20,10 @@ pragma solidity ^0.4.24;
 
 contract IAssetProxyDispatcher {
 
-    /// @dev Registers an asset proxy to an asset proxy id.
-    ///      An id can only be assigned to a single proxy at a given time.
-    /// @param assetProxyId Id to register`newAssetProxy` under.
-    /// @param newAssetProxy Address of new asset proxy to register, or 0x0 to unset assetProxyId.
-    /// @param oldAssetProxy Existing asset proxy to overwrite, or 0x0 if assetProxyId is currently unused.
-    function registerAssetProxy(
-        bytes4 assetProxyId,
-        address newAssetProxy,
-        address oldAssetProxy
-    )
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
         external;
 
     /// @dev Gets an asset proxy.

packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol

@@ -54,8 +54,7 @@ contract LibExchangeErrors {
     string constant FAILED_EXECUTION = "FAILED_EXECUTION";                              // Transaction execution failed. 
     
     /// registerAssetProxy errors ///
-    string constant ASSET_PROXY_MISMATCH = "ASSET_PROXY_MISMATCH";                      // oldAssetProxy proxy does not match currentAssetProxy. 
-    string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";                // newAssetProxyId does not match given assetProxyId.
+    string constant ASSET_PROXY_ALREADY_EXISTS = "ASSET_PROXY_ALREADY_EXISTS";          // AssetProxy with same id already exists.
 
     /// dispatchTransferFrom errors ///
     string constant ASSET_PROXY_DOES_NOT_EXIST = "ASSET_PROXY_DOES_NOT_EXIST";          // No assetProxy registered at given id.

packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol

@@ -26,10 +26,9 @@ contract MAssetProxyDispatcher is
 {
 
     // Logs registration of new asset proxy
-    event AssetProxySet(
+    event AssetProxyRegistered(
         bytes4 id,              // Id of new registered AssetProxy.
-        address newAssetProxy,  // Address of new registered AssetProxy.
-        address oldAssetProxy   // Address of AssetProxy that was overwritten at given id (or null address).
+        address assetProxy      // Address of new registered AssetProxy.
     );
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.

packages/contracts/src/utils/core_combinatorial_utils.ts

@@ -96,8 +96,8 @@ export async function coreCombinatorialUtilsFactoryAsync(
         zrxAssetData,
     );
     const exchangeWrapper = new ExchangeWrapper(exchangeContract, provider);
-    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, ownerAddress);
-    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, ownerAddress);
+    await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, ownerAddress);
+    await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, ownerAddress);
 
     await web3Wrapper.awaitTransactionSuccessAsync(
         await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchangeContract.address, {

packages/contracts/src/utils/exchange_wrapper.ts

@@ -1,12 +1,10 @@
-import { AssetProxyId, SignedOrder } from '@0xproject/types';
+import { SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
-import * as _ from 'lodash';
 
 import { ExchangeContract } from '../generated_contract_wrappers/exchange';
 
-import { constants } from './constants';
 import { formatters } from './formatters';
 import { LogDecoder } from './log_decoder';
 import { orderUtils } from './order_utils';
@@ -192,20 +190,10 @@ export class ExchangeWrapper {
         return tx;
     }
     public async registerAssetProxyAsync(
-        assetProxyId: AssetProxyId,
         assetProxyAddress: string,
         from: string,
-        opts: { oldAssetProxyAddressIfExists?: string } = {},
     ): Promise<TransactionReceiptWithDecodedLogs> {
-        const oldAssetProxyAddress = _.isUndefined(opts.oldAssetProxyAddressIfExists)
-            ? constants.NULL_ADDRESS
-            : opts.oldAssetProxyAddressIfExists;
-        const txHash = await this._exchange.registerAssetProxy.sendTransactionAsync(
-            assetProxyId,
-            assetProxyAddress,
-            oldAssetProxyAddress,
-            { from },
-        );
+        const txHash = await this._exchange.registerAssetProxy.sendTransactionAsync(assetProxyAddress, { from });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
     }