base structure of upgradable republic

contracts/deploy/DelegatedCall.sol

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+pragma solidity ^0.4.17;
+
+
+/**
+ * @title DelegatedCall
+ * @author Ricardo Guilherme Schmidt (Status Research & Development GmbH) 
+ * @dev Abstract contract that delegates calls by `delegated` modifier to result of `_target()`
+ */
+contract DelegatedCall {
+    /**
+     * @dev delegates the call of this function
+     */
+    modifier delegated {
+        require(_target().delegatecall(msg.data)); //require successfull delegate call to remote `_target()`
+        assembly {
+            let outSize := returndatasize 
+            let outDataPtr := mload(0x40) //load memory
+            returndatacopy(outDataPtr, 0, outSize) //copy last return into pointer
+            return(outDataPtr, outSize) 
+        }
+        assert(false); //should never reach here
+        _; //never will execute local logic
+    }
+
+    /**
+     * @dev defines the address for delegation of calls
+     */
+    function _target()
+        internal
+        constant
+        returns(address);
+
+}