39 lines
565 B
Go
39 lines
565 B
Go
package main
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import (
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"errors"
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"fmt"
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)
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type Bitcoin int
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type Stringer interface {
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String() string
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}
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type Wallet struct {
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balance Bitcoin
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}
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var ErrInsufficientFunds = errors.New("cannot withdraw, insufficient funds")
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func (w *Wallet) Deposit(amount Bitcoin) {
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w.balance += amount
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}
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func (w *Wallet) Withdraw(amount Bitcoin) error {
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if amount > w.balance {
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return ErrInsufficientFunds
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}
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w.balance -= amount
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return nil
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}
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func (w *Wallet) Balance() Bitcoin {
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return w.balance
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}
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func (b Bitcoin) String() string {
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return fmt.Sprintf("%d BTC", b)
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}
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