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Clarify exception documentation

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Alex Beregszaszi 2017-06-16 18:14:21 +01:00 committed by chriseth
parent 64067975e4
commit 784b72bb72
1 changed files with 5 additions and 6 deletions
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docs/control-structures.rst
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@ -376,17 +376,17 @@ series of function calls that will reach a failing assertion. If this is possibl
in your contract you should fix. in your contract you should fix.
There are two other ways to trigger execptions: The ``revert`` function can be used to flag an error and There are two other ways to trigger execptions: The ``revert`` function can be used to flag an error and
revert the current call. In the future, it might be possible, to also include details about the error revert the current call. In the future it might be possible to also include details about the error
in a call to ``revert``. The ``throw`` keyword can also be used as an alternative to ``revert()``. in a call to ``revert``. The ``throw`` keyword can also be used as an alternative to ``revert()``.
When exceptions happen in a sub-call, they "bubble up" automatically. Exceptions to this rule are ``send`` When exceptions happen in a sub-call, they "bubble up" (i.e. exceptions are rethrown) automatically. Exceptions to this rule are ``send``
and the low-level functions ``call``, ``delegatecall`` and ``callcode`` -- those return ``false`` in case and the low-level functions ``call``, ``delegatecall`` and ``callcode`` -- those return ``false`` in case
of an exception instead of "rethrowing" it. of an exception instead of "bubbling up".
Catching exceptions is not yet possible. Catching exceptions is not yet possible.
In the following example, you can see how ``require`` can be used to easily check conditions on inputs In the following example, you can see how ``require`` can be used to easily check conditions on inputs
and the caller and how ``assert`` can be used for internal error checking:: and how ``assert`` can be used for internal error checking::
pragma solidity ^0.4.0; pragma solidity ^0.4.0;
@ -403,8 +403,7 @@ and the caller and how ``assert`` can be used for internal error checking::
} }
} }
Currently, Solidity automatically generates an exception in the following situations. These exceptions An ``assert``-style exception is generated in the following situations:
use the same mechanism as a failed ``assert`` call, i.e. they flag an internal error.
#. If you access an array at a too large or negative index (i.e. ``x[i]`` where ``i >= x.length`` or ``i < 0``). #. If you access an array at a too large or negative index (i.e. ``x[i]`` where ``i >= x.length`` or ``i < 0``).
#. If you access a fixed-length ``bytesN`` at a too large or negative index. #. If you access a fixed-length ``bytesN`` at a too large or negative index.