feat(if-else): add if-else access control

listings/ch00-introduction/if_else/.gitignore

@@ -0,0 +1 @@
+target

listings/ch00-introduction/if_else/Scarb.toml

@@ -0,0 +1,8 @@
+[package]
+name = "if_else"
+version = "0.1.0"
+
+[dependencies]
+starknet = "1.1.0"
+
+[[target.starknet-contract]]

listings/ch00-introduction/if_else/src/access_control.cairo

@@ -0,0 +1,23 @@
+use starknet::ContractAddress;
+
+#[contract]
+mod SimpleAccessControl {
+    use starknet::get_caller_address;
+
+    struct Storage {
+        owner: starknet::ContractAddress, 
+    }
+
+    #[constructor]
+    fn constructor(_address: starknet::ContractAddress) {
+        owner::write(_address);
+    }
+
+    #[external]
+    fn onlyOwner() -> bool {
+        if (get_caller_address() == owner::read()) {
+            return true;
+        }
+        return false;
+    }
+}

listings/ch00-introduction/if_else/src/lib.cairo

@@ -0,0 +1 @@
+mod access_control;