RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-10-18 18:42:46 +02:00
Code Issues Projects Releases Wiki Activity

[docs] Simplify some language for Error/cantFail in the programmer's manual.

Browse Source 
llvm-svn: 301773
This commit is contained in:
Lang Hames 2017-04-30 17:24:52 +00:00
parent 30cdb2efea
commit 6372ad3026
1 changed files with 9 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
docs/ProgrammersManual.rst
View File

@ -776,22 +776,21 @@ readability.
Using cantFail to simplify safe callsites Using cantFail to simplify safe callsites
""""""""""""""""""""""""""""""""""""""""" """""""""""""""""""""""""""""""""""""""""
Some functions may only fail for a subset of their inputs. For such functions Some functions may only fail for a subset of their inputs, so calls using known
call-sites using known-safe inputs can assume that the result will be a success safe inputs can be assumed to succeed.
value.
The cantFail functions encapsulate this by wrapping an assertion that their The cantFail functions encapsulate this by wrapping an assertion that their
argument is a success value and, in the case of Expected<T>, unwrapping the argument is a success value and, in the case of Expected<T>, unwrapping the
T value from the Expected<T> argument: T value:
.. code-block:: c++ .. code-block:: c++
Error mayFail(int X); Error onlyFailsForSomeXValues(int X);
Expected<int> mayFail2(int X); Expected<int> onlyFailsForSomeXValues2(int X);
void foo() { void foo() {
cantFail(mayFail(KnownSafeValue)); cantFail(onlyFailsForSomeXValues(KnownSafeValue));
int Y = cantFail(mayFail2(KnownSafeValue)); int Y = cantFail(onlyFailsForSomeXValues2(KnownSafeValue));
... ...
} }
@ -801,8 +800,8 @@ terminate the program on an error input, cantFile simply asserts that the result
is success. In debug builds this will result in an assertion failure if an error is success. In debug builds this will result in an assertion failure if an error
is encountered. In release builds the behavior of cantFail for failure values is is encountered. In release builds the behavior of cantFail for failure values is
undefined. As such, care must be taken in the use of cantFail: clients must be undefined. As such, care must be taken in the use of cantFail: clients must be
certain that a cantFail wrapped call really can not fail under any certain that a cantFail wrapped call really can not fail with the given
circumstances. arguments.
Use of the cantFail functions should be rare in library code, but they are Use of the cantFail functions should be rare in library code, but they are
likely to be of more use in tool and unit-test code where inputs and/or likely to be of more use in tool and unit-test code where inputs and/or