Program Patterns Basics

10 examples to get you started with Program Patterns - 7 basic and 3 intermediate.

Prerequisites

• PDAs, CPIs, and serialization basics from prior on-chain-rust sections.

Basic Examples

1. Init account pattern

Create + write discriminator + state.

// 1. create_account CPI 2. set disc 3. serialize State

• Reject reinit if lamports > 0.
• Payer signs rent.
• See account initialization patterns.

2. Vault PDA custody

Program holds funds via PDA authority.

// seeds [b"vault", user] + invoke_signed transfers

• Business rules before sign.
• Per-user seeds.
• Token + SOL variants.

3. Authority check

Stored pubkey must sign or match PDA.

if !authority.is_signer { return Err(...); }

• Role separation admin vs user.
• Two-step ownership transfer.
• Avoid single global admin.

4. State machine enum

Account stores status; ix validate transitions.

enum Status { Open, Filled, Cancelled }

• Illegal transition returns error.
• Terminal states reject further ops.
• Emit event on transition.

5. Fee collection

Split amount to treasury on action.

let fee = amount.checked_mul(bps)?.checked_div(10000)?;

• Checked math.
• Treasury PDA or ATA.
• Document fee bps immutably or via config.

6. Clock-based expiry

Read Clock sysvar for deadlines.

let clock = Clock::get()?;
if clock.unix_timestamp > deadline { return Err(...); }

• Slots vs unix time.
• Validator clock trustworthy within bounds.
• Grace periods explicit.

7. Close account

Zero data, transfer lamports, mark closed.

// zero data, transfer rent to recipient

• Prevent revival attacks.
• Only authority may close.
• Anchor close constraint pattern.

Intermediate Examples

8. Escrow release

Conditions + token CPI from escrow PDA.

// verify + invoke_signed token transfer

• CEI ordering.
• Reentrancy aware.
• See vault & escrow page.

Related: Vault & Escrow

9. Config account

Global params with admin rotate.

struct Config { admin: Pubkey, fee_bps: u16 }

• Timelock optional.
• Bounds on fee_bps.
• Upgrade-safe layout.

Related: Access Control & Authorities

10. Versioned schema

Migration ix for layout v2.

if version == 1 { migrate_v1_to_v2()? }

• Lazy migration.
• Dual-read window.
• See upgrade-safe design.

Related: Upgrade-Safe Data Design

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.