diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/frequently-asked-questions.rst | 38 | ||||
| -rw-r--r-- | docs/installing-solidity.rst | 2 | ||||
| -rw-r--r-- | docs/introduction-to-smart-contracts.rst | 2 | ||||
| -rw-r--r-- | docs/miscellaneous.rst | 4 | ||||
| -rw-r--r-- | docs/types.rst | 7 |
5 files changed, 12 insertions, 41 deletions
diff --git a/docs/frequently-asked-questions.rst b/docs/frequently-asked-questions.rst index e1a0e91b..bcdfdcd8 100644 --- a/docs/frequently-asked-questions.rst +++ b/docs/frequently-asked-questions.rst @@ -143,44 +143,6 @@ arguments for you. See `ping.sol <https://github.com/fivedogit/solidity-baby-steps/blob/master/contracts/45_ping.sol>`_ and `pong.sol <https://github.com/fivedogit/solidity-baby-steps/blob/master/contracts/45_pong.sol>`_. -When returning a value of say ``uint`` type, is it possible to return an ``undefined`` or "null"-like value? -============================================================================================================ - -This is not possible, because all types use up the full value range. - -You have the option to ``throw`` on error, which will also revert the whole -transaction, which might be a good idea if you ran into an unexpected -situation. - -If you do not want to throw, you can return a pair:: - - pragma solidity >0.4.23 <0.6.0; - - contract C { - uint[] counters; - - function getCounter(uint index) - public - view - returns (uint counter, bool error) { - if (index >= counters.length) - return (0, true); - else - return (counters[index], false); - } - - function checkCounter(uint index) public view { - (uint counter, bool error) = getCounter(index); - if (error) { - // Handle the error - } else { - // Do something with counter. - require(counter > 7, "Invalid counter value"); - } - } - } - - Are comments included with deployed contracts and do they increase deployment gas? ================================================================================== diff --git a/docs/installing-solidity.rst b/docs/installing-solidity.rst index f8de0e8d..2797d8b0 100644 --- a/docs/installing-solidity.rst +++ b/docs/installing-solidity.rst @@ -115,7 +115,7 @@ Arch Linux also has packages, albeit limited to the latest development version: pacman -S solidity -We distribute the Solidity compiler through Homebrow +We distribute the Solidity compiler through Homebrew as a build-from-source version. Pre-built bottles are currently not supported. diff --git a/docs/introduction-to-smart-contracts.rst b/docs/introduction-to-smart-contracts.rst index 9245300b..34ef012e 100644 --- a/docs/introduction-to-smart-contracts.rst +++ b/docs/introduction-to-smart-contracts.rst @@ -400,7 +400,7 @@ within a word). At the time of expansion, the cost in gas must be paid. Memory i costly the larger it grows (it scales quadratically). The EVM is not a register machine but a stack machine, so all -computations are performed on an data area called the **stack**. It has a maximum size of +computations are performed on a data area called the **stack**. It has a maximum size of 1024 elements and contains words of 256 bits. Access to the stack is limited to the top end in the following way: It is possible to copy one of diff --git a/docs/miscellaneous.rst b/docs/miscellaneous.rst index cc2ba801..017d5b81 100644 --- a/docs/miscellaneous.rst +++ b/docs/miscellaneous.rst @@ -15,6 +15,10 @@ Statically-sized variables (everything except mapping and dynamically-sized arra - If an elementary type does not fit the remaining part of a storage slot, it is moved to the next storage slot. - Structs and array data always start a new slot and occupy whole slots (but items inside a struct or array are packed tightly according to these rules). +For contracts that use inheritance, the ordering of state variables is determined by the +C3-linearized order of contracts starting with the most base-ward contract. If allowed +by the above rules, state variables from different contracts do share the same storage slot. + .. warning:: When using elements that are smaller than 32 bytes, your contract's gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller diff --git a/docs/types.rst b/docs/types.rst index b84d3222..69c846a6 100644 --- a/docs/types.rst +++ b/docs/types.rst @@ -13,6 +13,11 @@ Solidity provides several elementary types which can be combined to form complex In addition, types can interact with each other in expressions containing operators. For a quick reference of the various operators, see :ref:`order`. +The concept of "undefined" or "null" values does not exist in Solidity, but newly +declared variables always have a :ref:`default value<default-value>` dependent +on its type. To handle any unexpected values, you should use the :ref:`revert function<assert-and-require>` to revert the whole transaction, or return a +tuple with a second `bool` value denoting success. + .. index:: ! value type, ! type;value Value Types @@ -273,7 +278,7 @@ Example:: when the call returns. The regular way to interact with other contracts is to call a function on a contract object (``x.f()``). -:: note:: +.. note:: Previous versions of Solidity allowed these functions to receive arbitrary arguments and would also handle a first argument of type ``bytes4`` differently. These edge cases were removed in version 0.5.0. |