Smart Contract Interface

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Pronunciation

[smahrt kon-trakt in-ter-face]

Analogy

A smart contract interface is like a restaurant menu—it lists available dishes (functions) without revealing the kitchen’s recipes (implementation).

Definition

An abstract definition of a contract’s functions and events in that specifies how other contracts can interact without exposing implementation.

Key Points Intro

Interfaces enable modular interactions through:

Key Points

Function signatures only: No implementation bodies.

No state variables or constructors allowed.

ABI compliance: Ensures correct encoding/decoding.

Multiple inheritance: Contracts can implement many interfaces.

Example

``` interface IERC20 { function transfer(address to, uint256 amt) external returns (bool); } ```

Technical Deep Dive

Interfaces compile to entries without . A contract implementing an interface must match its function selectors. The uses the interface’s selector to route calls. Interfaces facilitate upgradeability and cross‑contract type safety.

Security Warning

Mismatched interface and implementation selectors can lock funds; verify selectors via `bytes4(keccak256(...))`.

Caveat

Interfaces cannot enforce behavioral invariants—only signature compliance.

Related Terms

Blockchain & Cryptocurrency Glossary

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