diff --git a/docs/frequently-asked-questions.rst b/docs/frequently-asked-questions.rst index 6ac5a9e94..fc7d7b7fe 100644 --- a/docs/frequently-asked-questions.rst +++ b/docs/frequently-asked-questions.rst @@ -666,6 +666,23 @@ gas and return your 20 Wei). In the above example, the low-level function `call` is used to invoke another contract with `p.data` as payload and `p.amount` Wei is sent with that call. +What happens to a struct's mapping when copying over a struct? +============================================================== + +This is a very interesting question. Suppose that we have a contract field set up like such:: + + struct user{ + mapping(string => address) usedContracts; + } + function somefunction{ + user user1; + user1.usedContracts["Hello"] = "World"; + user user2 = user1; + } + +In this case, the mapping of the struct being copied over into the userList is ignored as there is no "list of mapped keys". +Therefore it is not possible to find out which values should be copied over. + How do I initialize a contract with only a specific amount of wei? ==================================================================