Merge pull request #497 from thehubbleproject/more-immutables

Add the rest of the immutables

contracts/DepositManager.sol

@@ -87,10 +87,11 @@ contract DepositCore is SubtreeQueue {
 contract DepositManager is DepositCore, IDepositManager {
     using Types for Types.UserState;
     using SafeERC20 for IERC20;
-    address public vault;
+    address public immutable vault;
+    // Can't be immutable yet. Since the rollup is deployed after DepositManager
     address public rollup;
 
-    ITokenRegistry public tokenRegistry;
+    ITokenRegistry public immutable tokenRegistry;
 
     modifier onlyRollup() {
         require(

contracts/Vault.sol

@@ -13,9 +13,10 @@ contract Vault {
     using Types for Types.MassMigrationCommitment;
     using Types for Types.Batch;
 
+    // Can't be immutable yet. Since the rollup is deployed after Vault
     Rollup public rollup;
-    SpokeRegistry public spokes;
-    ITokenRegistry public tokenRegistry;
+    SpokeRegistry public immutable spokes;
+    ITokenRegistry public immutable tokenRegistry;
 
     mapping(uint256 => uint256) private bitmap;
 

contracts/WithdrawManager.sol

@@ -15,14 +15,15 @@ contract WithdrawManager {
     using Tx for bytes;
     using Types for Types.UserState;
     using SafeERC20 for IERC20;
-    Vault public vault;
 
     // withdrawRoot => a bitmap of whether a publicIndex owner has the token claimed
     mapping(bytes32 => mapping(uint256 => uint256)) private bitmap;
     // withdrawRoot => accountRoot
     mapping(bytes32 => bytes32) private processed;
-    ITokenRegistry public tokenRegistry;
-    bytes32 public appID;
+
+    ITokenRegistry public immutable tokenRegistry;
+    Vault public immutable vault;
+    bytes32 public immutable appID;
 
     constructor(
         ITokenRegistry _tokenRegistry,

contracts/client/FrontendUtilities.sol

@@ -6,8 +6,8 @@ import { DepositManager } from "../DepositManager.sol";
 import { BLSAccountRegistry } from "../BLSAccountRegistry.sol";
 
 contract FrontendUtilities {
-    DepositManager public depositManager;
-    BLSAccountRegistry public accountRegistry;
+    DepositManager public immutable depositManager;
+    BLSAccountRegistry public immutable accountRegistry;
 
     constructor(
         DepositManager _depositManager,

contracts/proposers/BurnAuction.sol

@@ -12,13 +12,13 @@ contract BurnAuction is Chooser {
 
     // donation numerator and demoninator are used to calculate donation amount
     uint256 public constant DONATION_DENOMINATOR = 10000;
-    uint256 public donationNumerator;
+    uint256 public immutable donationNumerator;
 
     // Donation address that is fed with portion of burned amount
-    address payable public donationAddress;
+    address payable public immutable donationAddress;
 
     // First block where the first slot begins
-    uint256 public genesisBlock;
+    uint256 public immutable genesisBlock;
 
     // Bid is a structure indicating that
     // "coordinator" is willing to burn certain
@@ -50,7 +50,7 @@ contract BurnAuction is Chooser {
         public
     {
         require(
-            donationNumerator <= DONATION_DENOMINATOR,
+            _donationNumerator <= DONATION_DENOMINATOR,
             "BurnAuction, constructor: bad denominator"
         );