| Variables in Rust do more than just hold data in the stack, they can also *own* |
| resources, e.g. `Box<T>` owns memory in the heap. Because Rust enforces the |
| [RAII](http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization) |
| discipline, whenever an object goes out of scope, its destructor is called |
| and the resources *owned* by it are freed. This behavior shields against |
| *resource leak* bugs. |
| |
| {raii.play} |
| |
| Don't take my word for it, let's check using `valgrind` |
| |
| ``` |
| $ rustc raii.rs && valgrind ./raii |
| ==26873== Memcheck, a memory error detector |
| ==26873== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. |
| ==26873== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info |
| ==26873== Command: ./raii |
| ==26873== |
| ==26873== |
| ==26873== HEAP SUMMARY: |
| ==26873== in use at exit: 0 bytes in 0 blocks |
| ==26873== total heap usage: 1,013 allocs, 1,013 frees, 8,696 bytes allocated |
| ==26873== |
| ==26873== All heap blocks were freed -- no leaks are possible |
| ==26873== |
| ==26873== For counts of detected and suppressed errors, rerun with: -v |
| ==26873== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2) |
| ``` |
| |
| You'll never have to manually free memory again or worry about memory leaks! |
