Michael Schimmel
51 lines
1.5 KiB
Plaintext
51 lines
1.5 KiB
Plaintext
;; Output: [150 130 "Insufficient funds" 130]
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; ---------------------------------------------------------
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; Object-Oriented Records Example
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; ---------------------------------------------------------
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; This showcase treats a record as an object by storing
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; closures that capture private state.
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(do
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; A factory function (Constructor) for a BankAccount object
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(def make-account (fn [initial-balance]
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(do
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; 'balance' is a captured parameter, acting as private state
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(def balance initial-balance)
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{
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; Method: Get current balance
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:balance (fn [] balance)
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; Method: Deposit money
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:deposit (fn [amount]
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(assign balance (+ balance amount)))
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; Method: Withdraw money with validation
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:withdraw (fn [amount]
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(if (>= balance amount)
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(assign balance (- balance amount))
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"Insufficient funds"))
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}
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)))
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; 1. Create an instance
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(def my-acc (make-account 100))
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; 2. Call 'deposit' method
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; Note the double parens: (.deposit my-acc) gets the function, then we call it
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(def b1 ((.deposit my-acc) 50)) ; balance is now 150
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; 3. Call 'withdraw' method
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(def b2 ((.withdraw my-acc) 20)) ; balance is now 130
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; 4. Call 'withdraw' with invalid amount
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(def error-msg ((.withdraw my-acc) 1000))
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; 5. Call 'balance' getter
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(def final-balance ((.balance my-acc)))
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; Return summary of operations
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[b1 b2 error-msg final-balance]
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)
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