keepalive 1.0.0

Keepalive functionality

This is a small function to require pointers are stored on the stack. It guarantees that the pointer should be stored on the stack for at least the current scope.

This library implementation has 2 versions, the normal version which just adds a destructor to a struct, and one which calls an opaque function. The opaque function so far has not proven necessary, but is there in case a sufficiently intelligent optimizer is found that will circumvent the dead store.

Usage is pretty simple:

auto c = keepalive(new C); // c will be stored on the stack
functionTakingC(c); // auto-converts to a C

When to use

This is intended as a way to ensure stack storage for a pointer. This ensures that the GC can find the pointer. In most cases, if you are using this pointer later, it will be availble to the GC without this mechanism. The only time you would need to use this is if you are NOT using it later, AND it's only stored elsewhere in a location that the GC cannot find. In this case, its lifetime is only guaranteed to the end of the scope in which you called the keepalive function.

In most cases, using a deterministic registration and deregistration of a pointer is preferred, instead of letting the GC clean this up.

References:

• C# KeepAlive function
• Go KeepAlive function
• Dlang specification on C Interfacing