The view Functions

Understanding view functions

Solidity contracts have view functions, sometimes known as read-only functions. They allow us to query the contract’s state without changing it. This attribute is critical for security because it allows third-party users to retrieve data from the blockchain without fear of unintentional state changes. They include the following key properties:

• Non-state-changing: As the name implies, they don’t affect the state of the contract. They exist solely to read and query data.

• Gas-free for callers: Callers don’t consume gas fees when calling a view function from outside parties or contracts. This means that anyone can use these functions with no transaction fee.

• Immutable: They’re ideal for retrieving data that doesn’t change over time, such as configuration settings, balances, or contract-specific information.

Use cases of view functions

• Querying balances: They’re frequently used to verify the balance of an account or token. For example, a view function can return the balance of a specific Ethereum address.

• Configuration settings: They’re useful for retrieving contract configuration parameters, such as the contract owner, contract version, or contract-specific settings.

• Token information: They can offer information about token supply, ownership, or token metadata in the context of ERC-20 or ERC-721 tokens.

• Validation: They can be used to validate data without changing the state of the contract, e.g., checking the accuracy of input parameters.

Characteristics of view functions

To be recognized as a view function, a function must adhere to the following principles and constraints:

• Read-only function: A view function can’t affect any state variables defined in the contract. Attempting to alter state variables within a view function will result in a compilation warning.

• No Ether transfers: A view function can’t send or receive Ether. They’re only used to query data.

• No external contract creation: A view function isn’t permitted to create new contracts by using the selfdestruct operation or executing any other activity that alters the composition of the contract.

• No emitting events: A view function should not generate events. Event emission is reserved for functions that change the contract’s state.