Solana: How to infer or find basic types for return values in @solana/web3.js v2 library?

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Getting Return Types in @solana/web3.js v2: A Guide

As a developer working with Solana web3.js v2, you may have come across situations where you had to infer or find the correct type of a function’s return value. In this article, we will explore exactly how to do that.

Understanding the Problem

In @solana/web3.js v2, types are used to define the form and structure of data. When you call functions on the Solana blockchain, you typically pass parameters as an array or object of a specific type. However, when a function returns a value, it is not always clear what type the return value is.

Basic types in @solana/web3.js v2

To understand how to infer the return type of a function, let’s first look at some basic types in Solana web3.js v2:

• “Uint8Array”: An array of 256 unsigned 8-bit integers

• “U8”: A single unsigned 8-bit integer

• “Byte32”: A 32-byte block of data encoded as an array of bytes

• “String”: A sequence of Unicode characters

• “BigInt”: A decimal number with arbitrary precision

• “Fixed64”: A 64-bit fixed-point value with precision up to 18 digits

Retrieval types

To infer the return type of a function, you need to parse the function signature and all the parameters passed. Here are some tips:

• Inspect the function signature

  : Look at the function name, arguments, and return type.

• Analyze parameter types: Check if each argument has a specific type (e.g. “Uint8Array”, “U8”, etc.). You can use the “typeof” operator or the “instanceof” method to check the type of the argument.

• Look for data types in the function body

  

  : If the return value is stored as a byte array, you may be able to infer its size by analyzing how it is encoded.

Example: Deriving the return type

Let’s take a simple example:

const deploy = async (account: string) => {
// ... deployment logic ...
};

In this case, the “deploy” function uses a “string” parameter “account”. The return value is stored as a byte array.

To get its size, we can parse the function field:

const deploy = async (account: string) => {
// ... deployment logic ...
const result = await deployAccount(account);
console.log(result.length); // prints 24 bytes
};

In this case, the return value is a byte array with 24 elements.

Determining return types

If you are not sure about the type of a function or its return values, you can use the following methods:

• Use the @solana/web3.js v2 documentation: Check the official @solana/web3.js v2 documentation to see what types are provided for each function signature.

• Check your code base: Look at the source code of your project or library to see how return values ​​are handled and inferred.

• Use a type checker such as “ts-jest” or “jest-extended”. These libraries can help you identify errors and infer types.

In general, inferring or finding the underlying return types of @solana/web3.js v2 involves analyzing the function signature, parameter types, and data structures that are stored as returns. By following these tips and using tools like a type checker and documentation, you can write more robust and maintainable code in Solana.