ft-transfer?

Function Signature

(ft-transfer? token-name amount sender recipient)

• Input:
  • token-name: The name of the fungible token
  • amount: The amount of tokens to transfer (uint)
  • sender: The principal sending the tokens
  • recipient: The principal receiving the tokens
• Output: (response bool uint)

Why it matters

The ft-transfer? function is crucial for:

1. Moving fungible tokens between different principals within a smart contract.
2. Implementing token transfer functionality in decentralized applications.
3. Enabling token-based transactions and interactions between users or contracts.
4. Facilitating token economy mechanisms within smart contracts.

When to use it

Use ft-transfer? when you need to:

• Transfer tokens from one account to another.
• Implement payment or reward systems using custom tokens.
• Allow users to send tokens to each other within your dApp.
• Move tokens as part of more complex contract operations.

Best Practices

• Always check the return value to ensure the transfer was successful.
• Implement proper access controls to prevent unauthorized transfers.
• Consider using asserts! or try! to handle transfer failures gracefully.
• Be aware that any principal can call this function, so add necessary guards.
• Verify sender has sufficient balance before attempting a transfer.

Practical Example: Token Transfer Function

Let's implement a public function for transferring tokens with some basic checks:

(define-fungible-token my-token)

(define-public (transfer-tokens (amount uint) (recipient principal))
  (let ((sender tx-sender))
    (asserts! (not (is-eq sender recipient)) (err u2))
    (asserts! (> amount u0) (err u3))
    (match (ft-transfer? my-token amount sender recipient)
      success (ok success)
      error (err error))))

;; Usage
(ft-mint? my-token u100 tx-sender)
(transfer-tokens u50 'SPAXYA5XS51713FDTQ8H94EJ4V579CXMTRNBZKSF) ;; Returns (ok true)

This example demonstrates:

1. Using ft-transfer? within a public function to transfer tokens.
2. Implementing basic checks for valid transfer conditions.
3. Handling the response from ft-transfer? and propagating it to the caller.

Common Pitfalls

1. Forgetting that ft-transfer? can be called by any principal, potentially leading to unauthorized transfers.
2. Not handling all possible error cases returned by ft-transfer?.
3. Attempting to transfer more tokens than the sender's balance.
4. Using ft-transfer? with a token name that hasn't been defined in the contract.

Related Functions

• ft-mint?: Used to create new tokens and assign them to a principal.
• ft-burn?: Used to destroy tokens, reducing the balance of a principal.
• ft-get-balance: Used to check the token balance of a principal.
• ft-get-supply: Used to get the current total supply of tokens.

Conclusion

The ft-transfer? function is a fundamental component for implementing token transfers in Clarity smart contracts. It provides a straightforward way to move tokens between principals, enabling a wide range of token-based functionalities. When used with proper checks and balances, it allows for the creation of secure and efficient token economies within decentralized applications on the Stacks blockchain.