Gas Optimizations

[code423n4]

AN ARRAY’S LENGTH SHOULD BE CACHED TO SAVE GAS IN FOR-LOOPS

File:   main/src/utils/GobblerReserve.sol   #1
37            for (uint256 i = 0; i < ids.length; i++) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

  File: main/src/utils/token/GobblersERC1155B.sol #2 114 for (uint256 i = 0; i < owners.length; ++i) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L114

State Variables declared only set in the constructor should be declared immutable

File:   main/src/utils/token/GobblersERC721.sol   #1
23    string public name;

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L23

  File: main/src/utils/token/GobblersERC721.sol #2 25 string public symbol;

https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L25

++i costs less gas than i++, especially when it’s used in for-loops (--i/i-- too)

Saves 6 gas PER LOOP

File:   main/src/Pages.sol   #1
251            for (uint256 i = 0; i < numPages; i++) _mint(community, ++lastMintedPageId);

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L251

  File: main/src/utils/GobblerReserve.sol #2 37 for (uint256 i = 0; i < ids.length; i++) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

Using private rather than public for constants, saves gas

If needed, the value can be read from the verified contract source code

File:   main/src/ArtGobblers.sol   #1
112    uint256 public constant MAX_SUPPLY = 10000;

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L112

  File: main/src/ArtGobblers.sol #2 115 uint256 public constant MINTLIST_SUPPLY = 2000;

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L115

  File: main/src/ArtGobblers.sol #3 118 uint256 public constant LEGENDARY_SUPPLY = 10;

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L118

  File: main/src/ArtGobblers.sol #4 177 uint256 public constant LEGENDARY_GOBBLER_INITIAL_START_PRICE = 69;

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L177

It costs more gas to initialize variables to zero than to let the default of zero be applied

File:   main/src/ArtGobblers.sol   #1
432            for (uint256 i = 0; i < cost; ++i) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L432

  File: main/src/ArtGobblers.sol #2 592 for (uint256 i = 0; i < numGobblers; ++i) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L592

  File: main/src/Pages.sol #3 251 for (uint256 i = 0; i < numPages; i++) _mint(community, ++lastMintedPageId);

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L251

  File: main/src/utils/GobblerReserve.sol #4 37 for (uint256 i = 0; i < ids.length; i++) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

  File: main/src/utils/token/GobblersERC1155B.sol #5 114 for (uint256 i = 0; i < owners.length; ++i) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L114

  File: main/src/utils/token/GobblersERC1155B.sol #6 173 for (uint256 i = 0; i < amount; ++i) {

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L173

Use custom errors rather than revert()/require() strings to save deployment gas

Custom errors are available from solidity version 0.8.4. The instances below match or exceed that version

 File:   main/src/ArtGobblers.sol   #1
 696            if (gobblerId == 0) revert("NOT_MINTED"); // 0 is not a valid id for Art Gobblers.

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L696

  File: main/src/ArtGobblers.sol #2 705 if (gobblerId < FIRST_LEGENDARY_GOBBLER_ID) revert("NOT_MINTED");

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L705

  File: main/src/ArtGobblers.sol #3 711 revert("NOT_MINTED"); // Unminted legendaries and invalid token ids.

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L711

  File: main/src/Pages.sol #4 266 if (pageId == 0 || pageId > currentId) revert("NOT_MINTED");

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L266

  File: main/src/utils/token/GobblersERC721.sol #5 62 require((owner = getGobblerData[id].owner) != address(0), "NOT_MINTED");

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L62

  File: main/src/utils/token/GobblersERC721.sol #6 66 require(owner != address(0), "ZERO_ADDRESS");

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L66

Use Solidity version of atleast 0.8.15

• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Goo.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/PagesERC721.sol#L2
• https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/rand/RandProvider.sol#L2

[GalloDaSballo]

100 gas at most