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| author | Yoichi Hirai <i@yoichihirai.com> | 2017-07-26 22:45:37 +0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-07-26 22:45:37 +0800 |
| commit | 092c2815e5cb1cdc3ecd30325a67e55e92fe2f49 (patch) | |
| tree | 82894ca157e4678a9704a4e8c369d50fec707135 | |
| parent | 43002b7bb8973e02919f23dcea099cb9877e9579 (diff) | |
| parent | 9c676e796c8ad1b366bc30ef29bfb177974d16d6 (diff) | |
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Merge pull request #2631 from maurelian/maurelian_patch1
Clarify require and assert usage
| -rw-r--r-- | docs/control-structures.rst | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/docs/control-structures.rst b/docs/control-structures.rst index 128e6fae..a2fae0b3 100644 --- a/docs/control-structures.rst +++ b/docs/control-structures.rst @@ -381,13 +381,11 @@ Error handling: Assert, Require, Revert and Exceptions Solidity uses state-reverting exceptions to handle errors. Such an exception will undo all changes made to the state in the current call (and all its sub-calls) and also flag an error to the caller. The convenience functions ``assert`` and ``require`` can be used to check for conditions and throw an exception -if the condition is not met. The difference between the two is that ``assert`` should only be used for internal errors -and ``require`` should be used to check external conditions (invalid inputs or errors in external components). -The idea behind that is that analysis tools can check your contract and try to come up with situations and -series of function calls that will reach a failing assertion. If this is possible, this means there is a bug -in your contract you should fix. +if the condition is not met. The ``assert`` function should only be used to test for internal errors, and to check invariants. +The ``require`` function should be used to ensure valid conditions, such as inputs, or contract state variables are met, or to validate return values from calls to external contracts. +If used properly, analysis tools can evaluate your contract to identify the conditions and function calls which will reach a failing ``assert``. Properly functioning code should never it is reach a failing assert statement, if this happens there is a bug in your contract which 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 exceptions: 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 in a call to ``revert``. The ``throw`` keyword can also be used as an alternative to ``revert()``. |