About Smart Contract

If you are a smart contract developer, you will need to consider something about the contract:

• Clean: No unused code, nonsense comment,
• Well document: Comment to all functions
• Formatted: Reformat, reformat, reformat
• Unit test all functions
• Migration for testnet and mainnet
• Avoid duplication code, avoid using too many unnecessary modifiers to reduce contract size
• Upgradable

*Reusable, Replaceable, Upgradable, Testable => Easier maintenance*

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About some checklist in contract function

• Consider using nonReentrant modifier in paying function to avoid duplicate calls
• Use safe math to check about substract and div operators. Get revert if you div zero, or assign a negative number to uint.
• About percent calculation should use the rate nominator approach. MUL first, DIV last

uint internal constant RATE_NOMINATOR = 10000;
uint tax = 100; // 1%
uint taxAmount = (amount * tax) / RATE_NOMINATOR;

• Do not loop more than 500 in an array, use pagination for long array

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About how to write code and unit tests

• You need to clear the requirement first
• Define test cases in your note