import hashlib import uuid from datetime import datetime class SimpleWallet: def (self, user_id): self.user_id = user_id self.balance = 0.0 self.transactions = []

Want to go deeper? Try building a simple wallet with and add a mock payment gateway. You’ll learn more than any tutorial can teach. Have you built a payment or wallet system before? What was your biggest technical challenge? Let me know in the comments.

alice.deposit(100) print(alice.pay(30, bob))

self.balance -= amount recipient_wallet.balance += amount

self._log_transaction("SEND", amount, recipient_wallet.user_id) recipient_wallet._log_transaction("RECEIVE", amount, self.user_id)

print(f"Alice balance: $alice.balance") print(f"Bob balance: $bob.balance")

We all use e-wallets daily. Tap your phone, scan a QR code, or send money to a friend—it feels like magic. But as a developer, I know there’s a lot more happening under the hood.

def _log_transaction(self, txn_type, amount, counterparty=None): txn = "id": str(uuid.uuid4()), "type": txn_type, "amount": amount, "timestamp": datetime.utcnow().isoformat(), "counterparty": counterparty, "balance_after": self.balance self.transactions.append(txn) alice = SimpleWallet("alice_123") bob = SimpleWallet("bob_456")