Merge pull request #4321 from ethereum/contractConversion

[BREAKING] Disallow conversion between unrelated contract types.

3 files changed, 21 insertions, 2 deletions

diff --git a/docs/contracts.rst b/docs/contracts.rst
index e78c3ff7..e87c8a67 100644
--- a/docs/contracts.rst
+++ b/docs/contracts.rst
@@ -1,5 +1,7 @@
 .. index:: ! contract
 
+.. _contracts:
+
 ##########
 Contracts
 ##########
diff --git a/docs/frequently-asked-questions.rst b/docs/frequently-asked-questions.rst
index cb46dea6..c2df0d3a 100644
--- a/docs/frequently-asked-questions.rst
+++ b/docs/frequently-asked-questions.rst
@@ -379,7 +379,7 @@ In this example::
     }
 
     contract A {
-        address child;
+        B child;
 
         function test() public {
             child = (new B).value(10)(); //construct a new B with 10 wei
diff --git a/docs/types.rst b/docs/types.rst
index d6767b54..566c4c19 100644
--- a/docs/types.rst
+++ b/docs/types.rst
@@ -192,6 +192,23 @@ The ``.gas()`` option is available on all three methods, while the ``.value()``
 .. note::
     The use of ``callcode`` is discouraged and will be removed in the future.
 
+Contract Types
+--------------
+
+Every :ref:`contract<contracts>` defines its own type. Contracts can be implicitly converted
+to contracts they inherit from. They can be explicitly converted from and to ``address`` types.
+
+The data representation of a contract is identical to that of the ``address`` type and
+this type is also used in the :ref:`ABI<ABI>`.
+
+Contracts do not support any operators.
+
+The members of contract types are the external functions of the contract including
+public state variables.
+
+.. note::
+    Starting with version 0.5.0 contracts do not derive from the address type, but can still be explicitly converted to address.
+
 .. index:: byte array, bytes32
 
 
@@ -884,7 +901,7 @@ for each ``_KeyType``, recursively.
         function f() public returns (uint) {
             MappingExample m = new MappingExample();
             m.update(100);
-            return m.balances(this);
+            return m.balances(address(this));
         }
     }