[8] Other names for this idiom include Constructor Acquires, Destructor Releases (CADRe)[9] and one particular style of use is called Scope-based Resource Management (SBRM).
The following C++11 example demonstrates usage of RAII for file access and mutex locking: This code is exception-safe because C++ guarantees that all objects with automatic storage duration (local variables) are destroyed at the end of the enclosing scope in the reverse order of their construction.
[13] Using RAII greatly simplifies resource management, reduces overall code size and helps ensure program correctness.
Resource management therefore needs to be tied to the lifespan of suitable objects in order to gain automatic allocation and reclamation.
Resources are acquired during initialization, when there is no chance of them being used before they are available, and released with the destruction of the same objects, which is guaranteed to take place even in case of errors.
In both cases, RAII ensures only that the resource in question is released appropriately; care must still be taken to maintain exception safety.
Both Clang and the GNU Compiler Collection implement a non-standard extension to the C language to support RAII: the "cleanup" variable attribute.
RAII depends on heap-based objects to be implicitly or explicitly deleted along all possible execution paths, in order to trigger its resource-releasing destructor (or equivalent).
[citation needed] At the 2018 Gamelab conference, Jonathan Blow claimed that use of RAII can cause memory fragmentation which in turn can cause cache misses and a 100 times or worse hit on performance.
[19] Perl, Python (in the CPython implementation),[20] and PHP[21] manage object lifetime by reference counting, which makes it possible to use RAII.
However, it is not always idiomatic in such languages, and is specifically discouraged in Python (in favor of context managers and finalizers from the weakref package).