From 1475cde2889d0187c596304cbfa08a63e0e31f61 Mon Sep 17 00:00:00 2001 From: Chris Ward Date: Wed, 22 Aug 2018 14:28:43 +0200 Subject: Update Infofeed example code and explanation --- docs/control-structures.rst | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) (limited to 'docs') diff --git a/docs/control-structures.rst b/docs/control-structures.rst index d0e58908..3d056180 100644 --- a/docs/control-structures.rst +++ b/docs/control-structures.rst @@ -135,23 +135,18 @@ the gas can be specified with special options ``.value()`` and ``.gas()``, respe contract Consumer { InfoFeed feed; - function setFeed(address addr) public { feed = InfoFeed(addr); } + function setFeed(InfoFeed addr) public { feed = addr; } function callFeed() public { feed.info.value(10).gas(800)(); } } -The modifier ``payable`` has to be used for ``info``, because otherwise, the `.value()` -option would not be available. +You need to use the modifier ``payable`` with the ``info`` function because +otherwise, the ``.value()`` option would not be available. -Note that the expression ``InfoFeed(addr)`` performs an explicit type conversion stating -that "we know that the type of the contract at the given address is ``InfoFeed``" and -this does not execute a constructor. Explicit type conversions have to be -handled with extreme caution. Never call a function on a contract where you -are not sure about its type. +You can also use ``function setFeed(InfoFeed _feed) { feed = _feed; }`` +directly. -We could also have used ``function setFeed(InfoFeed _feed) { feed = _feed; }`` directly. -Be careful about the fact that ``feed.info.value(10).gas(800)`` -only (locally) sets the value and amount of gas sent with the function call and only the -parentheses at the end perform the actual call. +.. warning:: + Be careful that ``feed.info.value(10).gas(800)`` only locally sets the ``value`` and amount of ``gas`` sent with the function call, and the parentheses at the end perform the actual call. Function calls cause exceptions if the called contract does not exist (in the sense that the account does not contain code) or if the called contract itself -- cgit v1.2.3 From 7fc496b6ab23dd73f4ea7b1816ada21ec73ff254 Mon Sep 17 00:00:00 2001 From: Chris Ward Date: Wed, 5 Sep 2018 15:48:19 +0200 Subject: Remove unneeded paragraph --- docs/control-structures.rst | 3 --- 1 file changed, 3 deletions(-) (limited to 'docs') diff --git a/docs/control-structures.rst b/docs/control-structures.rst index 3d056180..5810aaa7 100644 --- a/docs/control-structures.rst +++ b/docs/control-structures.rst @@ -142,9 +142,6 @@ the gas can be specified with special options ``.value()`` and ``.gas()``, respe You need to use the modifier ``payable`` with the ``info`` function because otherwise, the ``.value()`` option would not be available. -You can also use ``function setFeed(InfoFeed _feed) { feed = _feed; }`` -directly. - .. warning:: Be careful that ``feed.info.value(10).gas(800)`` only locally sets the ``value`` and amount of ``gas`` sent with the function call, and the parentheses at the end perform the actual call. -- cgit v1.2.3