create static method

TransactionInstruction create(String memo, { List<Pubkey> signers = const [], })

Creates and returns an instruction which validates a string of UTF-8 encoded characters and verifies that any accounts provided are signers of the transaction. The program also logs the memo, as well as any verified signer addresses, to the transaction log, so that anyone can easily observe memos and know they were approved by zero or more addresses by inspecting the transaction log from a trusted provider.

Public keys passed in via the signerPubkeys will identify Signers which must subsequently sign the Transaction including the returned TransactionInstruction in order for the transaction to be valid.

• memo - The UTF-8 encoded memo string to validate.
• signers - An array of public keys which must sign the Transaction including the returned TransactionInstruction in order for the transaction to be valid and the memo verification to succeed. null is allowed if there are no signers for the memo verification.

Implementation

static TransactionInstruction create(
  final String memo, {
  final List<Pubkey> signers = const [],
}) {
  final List<AccountMeta> keys = [
    for (final Pubkey signer in signers)
      AccountMeta.signer(signer),
  ];

  final Iterable<u8> encoded = utf8.encode(memo);

  // A 32-byte public key takes up 44-bytes in length when converted to base58, each 8-bytes are
  // represented as 11-bytes.
  check((encoded.length + keys.length * 44) <= maxLength);

  final List<Iterable<u8>> data = [
    encoded,
  ];

  return _instance.createTransactionIntruction(
    MemoInstruction.create,
    keys: keys,
    data: data,
  );
}