Project Overview

This project is a banking system simulation written in Rust. It includes entities such as Wallets and Accounts, and uses traits, generics, and polymorphism to provide a flexible and extensible design.

Entities

Wallet

A Wallet can hold multiple accounts. It has a unique wallet_id and a wallet_type which can be either Basic or MultiCurrency.

Account

An Account represents a bank account with a specific currency. It has a unique account_number and an account_type which can be either Basic or Premium.

BasicWallet and MultiCurrencyWallet are two different implementations of the Wallet trait, each with its own unique characteristics.

BasicWallet

BasicWallet is a simple wallet that can hold only one account. It uses generics to allow for different types of accounts to be added to the wallet. The account is set during the creation of the BasicWallet, and it cannot be changed afterward. This design is suitable for scenarios where a wallet is expected to have only one account.

MultiCurrencyWallet

MultiCurrencyWallet, on the other hand, can hold multiple accounts, each with a different currency. Unlike BasicWallet, it does not use generics. Instead, it uses a vector to store multiple boxed Account trait objects. This allows for different types of accounts to be added to the wallet after its creation. This design is suitable for scenarios where a wallet is expected to handle multiple currencies.

The use of generics in BasicWallet and not in MultiCurrencyWallet is due to their different requirements. BasicWallet needs to know the exact type of its account at compile time, hence the use of generics. MultiCurrencyWallet needs to handle multiple accounts of potentially different types, hence the use of trait objects.

Traits, Generics, and Polymorphism

Traits

Traits are used to define shared behavior. In this project, the Wallet and Account traits define a common interface for all types of wallets and accounts.

Traits in Rust:

• Traits are used to define shared behavior.
• A trait is defined with the trait keyword, followed by the trait's name.
• Traits can have methods with or without default implementations.
• Traits can be implemented for any data type.
• Traits can be used as function parameters, enabling dynamic dispatch.
• Traits can be used as trait bounds on generic parameters, enabling static dispatch.
• Traits can inherit from other traits. This is done by specifying the parent trait in the trait definition.
• The child trait will then include the method signatures of the parent trait.

Generics

Generics are used in the Wallet trait to allow for different types of accounts to be added to a wallet. The BasicWallet struct is generic over the Account type, which allows it to hold any type that implements the Account trait. The MultiCurrencyWallet struct, on the other hand, uses trait objects to store multiple accounts of different types.

Generics in Rust:

• Generics are used to create functions and data types that can work with multiple types of data.
• Generics are declared using angle brackets where T is a placeholder for the type.
• The actual type for T is determined at compile time.
• Generics can be constrained by traits to only accept types that implement certain behaviors.
• Multiple generic types can be used by separating them with commas, like <T, U>.
• Lifetimes, which dictate how references to data should be handled, can also be generic.

Polymorphism

Polymorphism is used to allow for different types of wallets and accounts to be treated the same way. For example, a BasicWallet and a MultiCurrencyWallet can both be treated as a Wallet. a BasicAccount and a PremiumAccount can both be treated as an Account.

Polymorphism in Rust:

• Rust achieves polymorphism through the use of traits and trait objects.
• A trait defines a set of methods that a type must have to be considered as implementing that trait.
• Trait objects allow for multiple different types, each of which implement a particular trait, to be treated as the same general type.
• Trait objects are created by specifying a trait behind a reference, box, or other pointer type, like &dyn Trait or Box.
• Trait objects are dynamic and their type is checked at runtime.

Functions

Wallet Functions

• add_account: Adds an account to the wallet.
• balance: Returns the balance of the wallet for a specific currency.
• get_wallet_id: Returns the unique ID of the wallet.
• get_wallet_type: Returns the type of the wallet.
• find_account_index_by_currency: Finds the index of an account in the wallet by currency.
• get_account_number_by_index: Returns the account number of an account at a specific index in the wallet.
• get_account_by_currency: Returns an account in the wallet by currency.
• transfer: Transfers money from the wallet to another wallet.
• deposit: Deposits money into the wallet.
• withdraw: Withdraws money from the wallet.

Account Functions

• get_account_number: Returns the unique account number.
• get_account_type: Returns the type of the account.
• get_balance: Returns the balance of the account.
• get_currency: Returns the currency of the account.
• deposit: Deposits money into the account.
• withdraw: Withdraws money from the account.
• transfer: Transfers money from the account to another account.

Enums

WalletType

This enum represents the type of wallet. It can be either Basic or MultiCurrency.

AccountType

This enum represents the type of account. It can be either Basic or Premium.

ID Generation

The wallet_id and account_number are unique identifiers for wallets and accounts respectively.

Building and Testing

To build the project, navigate to the project directory and run the following command:

cargo build

To run the tests, use the following command:

cargo test

Please ensure that you have Rust and Cargo installed on your system before building or testing the project.