From bce79c975905ff21d9ced2f6412f0d209b587932 Mon Sep 17 00:00:00 2001
From: linnefromice <linnefromice@gmail.com>
Date: Wed, 9 Nov 2022 11:19:14 +0900
Subject: [PATCH 1/3] topic: Sui Patterns -> Hot Potato

---
 examples.sui.io/basics/Move.toml              |  1 +
 .../basics/sources/hot_potato.move            | 44 +++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 examples.sui.io/basics/sources/hot_potato.move

diff --git a/examples.sui.io/basics/Move.toml b/examples.sui.io/basics/Move.toml
index d78e24c..d3e5328 100644
--- a/examples.sui.io/basics/Move.toml
+++ b/examples.sui.io/basics/Move.toml
@@ -7,4 +7,5 @@ Sui = { git = "https://github.com/MystenLabs/sui.git", subdir = "crates/sui-fram
 
 [addresses]
 basics =  "0x0"
+patterns =  "0x0"
 sui =  "0000000000000000000000000000000000000002"
diff --git a/examples.sui.io/basics/sources/hot_potato.move b/examples.sui.io/basics/sources/hot_potato.move
new file mode 100644
index 0000000..a5eeb57
--- /dev/null
+++ b/examples.sui.io/basics/sources/hot_potato.move
@@ -0,0 +1,44 @@
+module patterns::trade_in {
+    use sui::coin::{Self, Coin};
+    use sui::transfer;
+    use sui::sui::SUI;
+    use sui::object::{Self, UID};
+    use sui::tx_context::{TxContext};
+
+    const MODEL_ONE_PRICE: u64 = 10000;
+    const MODEL_TWO_PRICE: u64 = 20000;
+    const EWrongModel: u64 = 1;
+    const EIncorrectAmount: u64 = 2;
+
+    struct Phone has key, store { id: UID, model: u8 }
+
+    struct Receipt { price: u64 }
+
+    public fun buy_phone(model: u8, ctx: &mut TxContext): (Phone, Receipt) {
+        assert!(model == 1 || model == 2, EWrongModel);
+        let price = if (model == 1) MODEL_ONE_PRICE else MODEL_TWO_PRICE;
+
+        (
+            Phone { id: object::new(ctx), model },
+            Receipt { price }
+        )
+    }
+
+    public fun pay_full(receipt: Receipt, payment: Coin<SUI>) {
+        let Receipt { price } = receipt;
+        assert!(coin::value(&payment) == price, EIncorrectAmount);
+        
+        transfer::transfer(payment, @patterns);
+    }
+
+    public fun trade_in(receipt: Receipt, old_phone: Phone, payment: Coin<SUI>) {
+        let Receipt { price } = receipt;
+        let tradein_price = if (old_phone.model == 1) MODEL_ONE_PRICE else MODEL_TWO_PRICE;
+        let to_pay = price - (tradein_price / 2);
+
+        assert!(coin::value(&payment) == to_pay, EIncorrectAmount);
+
+        transfer::transfer(old_phone, @patterns);
+        transfer::transfer(payment, @patterns);
+    }
+}

From 818b84b60a56b69359c0457e0b66094e6ccd4bc6 Mon Sep 17 00:00:00 2001
From: linnefromice <linnefromice@gmail.com>
Date: Wed, 9 Nov 2022 11:38:52 +0900
Subject: [PATCH 2/3] topic: Sui Patterns -> ID Pointer

---
 .../basics/sources/id_pointer.move            | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 examples.sui.io/basics/sources/id_pointer.move

diff --git a/examples.sui.io/basics/sources/id_pointer.move b/examples.sui.io/basics/sources/id_pointer.move
new file mode 100644
index 0000000..cfdff18
--- /dev/null
+++ b/examples.sui.io/basics/sources/id_pointer.move
@@ -0,0 +1,71 @@
+module patterns::lock_and_key {
+    use std::option::{Self, Option};
+    use sui::object::{Self, ID, UID};
+    use sui::tx_context::{Self, TxContext};
+    use sui::transfer;
+
+    const ELockIsEmpty: u64 = 0;
+    const EKeyMismatch: u64 = 1;
+    const ELockIsFull: u64 = 2;
+
+    struct Lock<T: store + key> has key {
+        id: UID,
+        locked: Option<T>
+    }
+
+    struct Key<phantom T: store + key> has key, store {
+        id: UID,
+        for: ID
+    }
+
+    public fun key_for<T: store + key>(key: &Key<T>): ID {
+        key.for
+    }
+
+    public entry fun create<T: store + key>(obj: T, ctx: &mut TxContext) {
+        let id = object::new(ctx);
+        let for = object::uid_to_inner(&id);
+
+        transfer::share_object(Lock<T> {
+            id,
+            locked: option::some(obj)
+        });
+
+        transfer::transfer(
+            Key<T> {
+                for,
+                id: object::new(ctx)
+            },
+            tx_context::sender(ctx)
+        );
+    }
+
+    public entry fun lock<T: store + key>(
+        obj: T,
+        lock: &mut Lock<T>,
+        key: &Key<T>
+    ) {
+        assert!(option::is_none(&lock.locked), ELockIsFull);
+        assert!(&key.for == object::borrow_id(lock), EKeyMismatch);
+
+        option::fill(&mut lock.locked, obj);
+    }
+
+    public entry fun unlock<T: store + key>(
+        lock: &mut Lock<T>,
+        key: &Key<T>
+    ): T {
+        assert!(option::is_some(&lock.locked), ELockIsEmpty);
+        assert!(&key.for == object::borrow_id(lock), EKeyMismatch);
+
+        option::extract(&mut lock.locked)
+    }
+
+    public fun take<T: store + key>(
+        lock: &mut Lock<T>,
+        key: &Key<T>,
+        ctx: &mut TxContext
+    ) {
+        transfer::transfer(unlock(lock, key), tx_context::sender(ctx));
+    }
+}
\ No newline at end of file

From 83d70a7b2d0cd1e65faac2da75ea3d177a7721de Mon Sep 17 00:00:00 2001
From: linnefromice <linnefromice@gmail.com>
Date: Wed, 9 Nov 2022 11:39:49 +0900
Subject: [PATCH 3/3] clean

---
 examples.sui.io/basics/sources/id_pointer.move | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples.sui.io/basics/sources/id_pointer.move b/examples.sui.io/basics/sources/id_pointer.move
index cfdff18..7d33714 100644
--- a/examples.sui.io/basics/sources/id_pointer.move
+++ b/examples.sui.io/basics/sources/id_pointer.move
@@ -68,4 +68,4 @@ module patterns::lock_and_key {
     ) {
         transfer::transfer(unlock(lock, key), tx_context::sender(ctx));
     }
-}
\ No newline at end of file
+}