added delegate call example to implementation of Upgradable Contracts learning project: A comprehensive educational resource for building upgradeable smart contracts on Ethereum and Base blockchain using Foundry and OpenZeppelin. Includes proxy patterns (Transparent, UUPS, Beacon), security best practices, test suites, deployment scripts, and detailed documentation with architectural explanations. Features SmallProxy.sol example, Foundry configuration, and structured learning modules for developers. - src/sublesson/DelegateCallExample.sol

Author: cypherpulse

src/sublesson/DelegateCallExample.sol

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.26;
+
+// NOTE: Deploy this contract first
+contract B {
+    // NOTE: storage layout must be the same as contract A
+    uint256 public num;
+    address public sender;
+    uint256 public value;
+
+    function setVars(uint256 _num) public payable {
+        num = _num;
+        sender = msg.sender;
+        value = msg.value;
+    }
+}
+
+contract A {
+    uint256 public num;
+    address public sender;
+    uint256 public value;
+
+    event DelegateResponse(bool success, bytes data);
+    event CallResponse(bool success, bytes data);
+
+    // Function using delegatecall
+    function setVarsDelegateCall(address _contract, uint256 _num)
+        public
+        payable
+    {
+        // A's storage is set; B's storage is not modified.
+        (bool success, bytes memory data) = _contract.delegatecall(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+
+        emit DelegateResponse(success, data);
+    }
+
+    // Function using call
+    function setVarsCall(address _contract, uint256 _num) public payable {
+        // B's storage is set; A's storage is not modified.
+        (bool success, bytes memory data) = _contract.call{value: msg.value}(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+
+        emit CallResponse(success, data);
+    }
+}