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| -rw-r--r-- | docs/contracts.rst | 17 | ||||
| -rw-r--r-- | docs/solidity-by-example.rst | 2 |
2 files changed, 15 insertions, 4 deletions
diff --git a/docs/contracts.rst b/docs/contracts.rst index ca15d814..4139190d 100644 --- a/docs/contracts.rst +++ b/docs/contracts.rst @@ -842,13 +842,14 @@ Solidity supports multiple inheritance by copying code including polymorphism. All function calls are virtual, which means that the most derived function is called, except when the contract name is explicitly given. -When a contract inherits from multiple contracts, only a single +When a contract inherits from other contracts, only a single contract is created on the blockchain, and the code from all the base contracts is copied into the created contract. The general inheritance system is very similar to `Python's <https://docs.python.org/3/tutorial/classes.html#inheritance>`_, -especially concerning multiple inheritance. +especially concerning multiple inheritance, but there are also +some :ref:`differences <multi-inheritance>`. Details are given in the following example. @@ -1064,6 +1065,8 @@ contracts' constructors, it will be abstract. .. index:: ! inheritance;multiple, ! linearization, ! C3 linearization +.. _multi-inheritance: + Multiple Inheritance and Linearization ====================================== @@ -1076,7 +1079,13 @@ disallows some inheritance graphs. Especially, the order in which the base classes are given in the ``is`` directive is important: You have to list the direct base contracts in the order from "most base-like" to "most derived". -Note that this order is different from the one used in Python. +Note that this order is the reverse of the one used in Python. + +Another simplifying way to explain this is that when a function is called that +is defined multiple times in different contracts, the given bases +are searched from right to left (left to right in Python) in a depth-first manner, +stopping at the first match. If a base contract has already been searched, it is skipped. + In the following code, Solidity will give the error "Linearization of inheritance graph impossible". @@ -1094,6 +1103,8 @@ The reason for this is that ``C`` requests ``X`` to override ``A`` requests to override ``X``, which is a contradiction that cannot be resolved. + + Inheriting Different Kinds of Members of the Same Name ====================================================== diff --git a/docs/solidity-by-example.rst b/docs/solidity-by-example.rst index adf00546..72b3581b 100644 --- a/docs/solidity-by-example.rst +++ b/docs/solidity-by-example.rst @@ -907,7 +907,7 @@ Each message includes the following information: * The smart contract's address, used to prevent cross-contract replay attacks. * The total amount of Ether that is owed the recipient so far. -A payment channel is closed just once, at the of a series of transfers. +A payment channel is closed just once, at the end of a series of transfers. Because of this, only one of the messages sent will be redeemed. This is why each message specifies a cumulative total amount of Ether owed, rather than the amount of the individual micropayment. The recipient will naturally choose to |