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Command Templates

Command templates define the syntax and parameters of the commands that can be sent via email to your smart contract. They consist of fixed strings and placeholders (matchers) that represent dynamic values.

A command is a predefined function within the EmailAuth.sol smart contract or a related contract that can be invoked via email authentication. Commands represent specific actions or operations that can be executed on the blockchain when properly authorized through the email verification process.

A command template consists of two main components that work together to define valid email commands:

  • Fixed Strings: Static parts of the command that do not change.
  • Matchers: Placeholders enclosed in curly braces {} that represent dynamic input values.
info
Transfer {uint} tokens to {ethAddr}

In this template:

  • Fixed Strings: "Transfer", "tokens to"
  • Matchers: {uint}, {ethAddr}

Available Type Matchers​

There are several types of matchers you can use in your command templates. Each matcher type allows you to capture different kinds of data from the command.

For a full list of matcher types and how to use them, see the following sections.

String Type Matcher​

The {string} matcher captures any string value. Solidity type: string. Use this matcher when you want to capture a text input.

Command Template

Set status message to {string}

Code Example

function commandTemplates() public pure returns (string[][] memory) {
    string[][] memory templates = new string[][](1);
    templates[0] = new string[](4);
    templates[0][0] = "Set";
    templates[0][1] = "status";
    templates[0][2] = "message";
    templates[0][3] = "{string}";
    return templates;
}

Uint Type Matcher​

The {uint} matcher captures an unsigned integer. Solidity type: uint256. Use this matcher when you need to capture a non-negative whole number.

Command Template

Deposit {uint} tokens

Code Example

function commandTemplates() public pure returns (string[][] memory) {
    string[][] memory templates = new string[][](1);
    templates[0] = new string[](3);
    templates[0][0] = "Deposit";
    templates[0][1] = "{uint}";
    templates[0][2] = "tokens";
    return templates;
}

Int Type Matcher​

The {int} matcher captures a signed integer. Solidity type: int256. Use this matcher when you need to capture both positive and negative whole numbers.

Command Template

Adjust balance by {int}

Code Example

function commandTemplates() public pure returns (string[][] memory) {
    string[][] memory templates = new string[][](1);
    templates[0] = new string[](5);
    templates[0][0] = "Adjust";
    templates[0][1] = "balance";
    templates[0][2] = "by";
    templates[0][3] = "{int}";
    return templates;
}

Decimals Type Matcher​

The {decimals} matcher captures a decimal number. Solidity type: uint256. Use this matcher when you need to capture numbers with decimal points.

For example, 2.7 is encoded as abi.encode(2.7 * (10**18)).

Command Template

Set exchange rate to {decimals}

Code Example

function commandTemplates() public pure returns (string[][] memory) {
    string[][] memory templates = new string[][](1);
    templates[0] = new string[](5);
    templates[0][0] = "Set";
    templates[0][1] = "exchange";
    templates[0][2] = "rate";
    templates[0][3] = "to";
    templates[0][4] = "{decimals}";
    return templates;
}

EthAddr Type Matcher​

The {ethAddr} matcher captures a checksummed Ethereum address in hexadecimal format. Solidity type: address. Use this matcher when you need to capture an Ethereum address.

Command Template

Authorize address {ethAddr}

Code Example

function commandTemplates() public pure returns (string[][] memory) {
    string[][] memory templates = new string[][](1);
    templates[0] = new string[](3);
    templates[0][0] = "Authorize";
    templates[0][1] = "address";
    templates[0][2] = "{ethAddr}";
    return templates;
}