8 files changed, 54 insertions, 21 deletions
diff --git a/src/0x.ts b/src/0x.ts
index 86976c4ab..fd7d9b5a5 100644
--- a/src/0x.ts
+++ b/src/0x.ts
@@ -170,13 +170,16 @@ export class ZeroEx {
             // We re-assign the send method so that Web3@1.0 providers work with 0x.js
             (provider as any).sendAsync = (provider as any).send;
         }
-        this._web3Wrapper = new Web3Wrapper(provider);
         const gasPrice = _.isUndefined(config) ? undefined : config.gasPrice;
-        this.token = new TokenWrapper(this._web3Wrapper, gasPrice);
-        this.proxy = new TokenTransferProxyWrapper(this._web3Wrapper, gasPrice);
-        this.exchange = new ExchangeWrapper(this._web3Wrapper, this.token, gasPrice);
-        this.tokenRegistry = new TokenRegistryWrapper(this._web3Wrapper, gasPrice);
-        this.etherToken = new EtherTokenWrapper(this._web3Wrapper, this.token, gasPrice);
+        const defaults = {
+            gasPrice,
+        };
+        this._web3Wrapper = new Web3Wrapper(provider, defaults);
+        this.token = new TokenWrapper(this._web3Wrapper);
+        this.proxy = new TokenTransferProxyWrapper(this._web3Wrapper);
+        this.exchange = new ExchangeWrapper(this._web3Wrapper, this.token);
+        this.tokenRegistry = new TokenRegistryWrapper(this._web3Wrapper);
+        this.etherToken = new EtherTokenWrapper(this._web3Wrapper, this.token);
     }
     /**
      * Sets a new web3 provider for 0x.js. Updating the provider will stop all
diff --git a/src/contract.ts b/src/contract.ts
index 0c76571cc..3592e0e71 100644
--- a/src/contract.ts
+++ b/src/contract.ts
@@ -6,11 +6,13 @@ export class Contract implements Web3.ContractInstance {
     public address: string;
     public abi: Web3.ContractAbi;
     private contract: Web3.ContractInstance;
+    private defaults: Partial<Web3.TxData>;
     [name: string]: any;
-    constructor(web3ContractInstance: Web3.ContractInstance) {
+    constructor(web3ContractInstance: Web3.ContractInstance, defaults: Partial<Web3.TxData>) {
         this.contract = web3ContractInstance;
         this.address = web3ContractInstance.address;
         this.abi = web3ContractInstance.abi;
+        this.defaults = defaults;
         this.populateEvents();
         this.populateFunctions();
     }
@@ -18,11 +20,12 @@ export class Contract implements Web3.ContractInstance {
         const functionsAbi = _.filter(this.abi, abiPart => abiPart.type === 'function');
         _.forEach(functionsAbi, (functionAbi: Web3.MethodAbi) => {
             const cbStyleFunction = this.contract[functionAbi.name];
-            this[functionAbi.name] = promisify(cbStyleFunction, this.contract);
             if (functionAbi.constant) {
+                this[functionAbi.name] = promisify(cbStyleFunction, this.contract);
                 const cbStyleCallFunction = this.contract[functionAbi.name].call;
                 this[functionAbi.name].call = promisify(cbStyleCallFunction, this.contract);
             } else {
+                this[functionAbi.name] = this.promisifyWithDefaultParams(cbStyleFunction);
                 const cbStyleEstimateGasFunction = this.contract[functionAbi.name].estimateGas;
                 this[functionAbi.name].estimateGas =
                     promisify(cbStyleEstimateGasFunction, this.contract);
@@ -35,4 +38,31 @@ export class Contract implements Web3.ContractInstance {
             this[eventAbi.name] = this.contract[eventAbi.name];
         });
     }
+    private promisifyWithDefaultParams(fn: (...args: any[]) => void): (...args: any[]) => Promise<any> {
+        const promisifiedWithDefaultParams = (...args: any[]) => {
+            const promise = new Promise((resolve, reject) => {
+                const lastArg = args[args.length - 1];
+                let txData: Partial<Web3.TxData> = {};
+                if (_.isObject(lastArg) && !_.isArray(lastArg) && !lastArg.isBigNumber) {
+                    txData = args.pop();
+                }
+                txData = {
+                    ...txData,
+                    ...this.defaults,
+                };
+                const callback = (err: Error, data: any) => {
+                    if (_.isNull(err)) {
+                        resolve(data);
+                    } else {
+                        reject(err);
+                    }
+                };
+                args.push(txData);
+                args.push(callback);
+                fn.apply(this.contract, args);
+            });
+            return promise;
+        };
+        return promisifiedWithDefaultParams;
+    }
 }
diff --git a/src/contract_wrappers/contract_wrapper.ts b/src/contract_wrappers/contract_wrapper.ts
index 3de26148f..ca19342f3 100644
--- a/src/contract_wrappers/contract_wrapper.ts
+++ b/src/contract_wrappers/contract_wrapper.ts
@@ -6,10 +6,8 @@ import {utils} from '../utils/utils';
 
 export class ContractWrapper {
     protected _web3Wrapper: Web3Wrapper;
-    private _gasPrice?: BigNumber.BigNumber;
-    constructor(web3Wrapper: Web3Wrapper, gasPrice?: BigNumber.BigNumber) {
+    constructor(web3Wrapper: Web3Wrapper) {
         this._web3Wrapper = web3Wrapper;
-        this._gasPrice = gasPrice;
     }
     protected async _instantiateContractIfExistsAsync<A extends Web3.ContractInstance>(artifact: Artifact,
                                                                                        address?: string): Promise<A> {
diff --git a/src/contract_wrappers/ether_token_wrapper.ts b/src/contract_wrappers/ether_token_wrapper.ts
index ba0cd05d8..4c19b3caa 100644
--- a/src/contract_wrappers/ether_token_wrapper.ts
+++ b/src/contract_wrappers/ether_token_wrapper.ts
@@ -13,8 +13,8 @@ import * as EtherTokenArtifacts from '../artifacts/EtherToken.json';
 export class EtherTokenWrapper extends ContractWrapper {
     private _etherTokenContractIfExists?: EtherTokenContract;
     private _tokenWrapper: TokenWrapper;
-    constructor(web3Wrapper: Web3Wrapper, tokenWrapper: TokenWrapper, gasPrice?: BigNumber.BigNumber) {
-        super(web3Wrapper, gasPrice);
+    constructor(web3Wrapper: Web3Wrapper, tokenWrapper: TokenWrapper) {
+        super(web3Wrapper);
         this._tokenWrapper = tokenWrapper;
     }
     /**
diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index 3b94bb22c..324c92062 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -72,8 +72,8 @@ export class ExchangeWrapper extends ContractWrapper {
         ];
         return [orderAddresses, orderValues];
     }
-    constructor(web3Wrapper: Web3Wrapper, tokenWrapper: TokenWrapper, gasPrice?: BigNumber.BigNumber) {
-        super(web3Wrapper, gasPrice);
+    constructor(web3Wrapper: Web3Wrapper, tokenWrapper: TokenWrapper) {
+        super(web3Wrapper);
         this._tokenWrapper = tokenWrapper;
         this._orderValidationUtils = new OrderValidationUtils(tokenWrapper, this);
         this._exchangeLogEventEmitters = [];
diff --git a/src/contract_wrappers/token_registry_wrapper.ts b/src/contract_wrappers/token_registry_wrapper.ts
index 1550bfa3e..57c9ca93d 100644
--- a/src/contract_wrappers/token_registry_wrapper.ts
+++ b/src/contract_wrappers/token_registry_wrapper.ts
@@ -11,8 +11,8 @@ import * as TokenRegistryArtifacts from '../artifacts/TokenRegistry.json';
  */
 export class TokenRegistryWrapper extends ContractWrapper {
     private _tokenRegistryContractIfExists?: TokenRegistryContract;
-    constructor(web3Wrapper: Web3Wrapper, gasPrice?: BigNumber.BigNumber) {
-        super(web3Wrapper, gasPrice);
+    constructor(web3Wrapper: Web3Wrapper) {
+        super(web3Wrapper);
     }
     /**
      * Retrieves all the tokens currently listed in the Token Registry smart contract
diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
index 9c72455f1..944f0fb42 100644
--- a/src/contract_wrappers/token_wrapper.ts
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -31,8 +31,8 @@ export class TokenWrapper extends ContractWrapper {
     public UNLIMITED_ALLOWANCE_IN_BASE_UNITS = constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
     private _tokenContractsByAddress: {[address: string]: TokenContract};
     private _tokenLogEventEmitters: ContractEventEmitter[];
-    constructor(web3Wrapper: Web3Wrapper, gasPrice?: BigNumber.BigNumber) {
-        super(web3Wrapper, gasPrice);
+    constructor(web3Wrapper: Web3Wrapper) {
+        super(web3Wrapper);
         this._tokenContractsByAddress = {};
         this._tokenLogEventEmitters = [];
     }
diff --git a/src/web3_wrapper.ts b/src/web3_wrapper.ts
index f3fe8a00b..a0923bef9 100644
--- a/src/web3_wrapper.ts
+++ b/src/web3_wrapper.ts
@@ -7,10 +7,12 @@ import {Contract} from './contract';
 
 export class Web3Wrapper {
     private web3: Web3;
+    private defaults: Partial<Web3.TxData>;
     private networkIdIfExists?: number;
-    constructor(provider: Web3.Provider) {
+    constructor(provider: Web3.Provider, defaults: Partial<Web3.TxData>) {
         this.web3 = new Web3();
         this.web3.setProvider(provider);
+        this.defaults = defaults;
     }
     public setProvider(provider: Web3.Provider) {
         delete this.networkIdIfExists;
@@ -97,7 +99,7 @@ export class Web3Wrapper {
     }
     private getContractInstance<A extends Web3.ContractInstance>(abi: Web3.ContractAbi, address: string): A {
         const web3ContractInstance = this.web3.eth.contract(abi).at(address);
-        const contractInstance = new Contract(web3ContractInstance) as any as A;
+        const contractInstance = new Contract(web3ContractInstance, this.defaults) as any as A;
         return contractInstance;
     }
     private async getNetworkAsync(): Promise<number> {