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registerFinalizer(ForeignObject,Function) -- register a finalizer for a foreign object

Description

If a foreign pointer object corresponds to memory that was not allocated by the GC garbage collector, then a function to properly deallocate this memory when the Pointer object that stores this pointer is garbage collected should be called. The function should take a single argument, a foreign object, typically of type voidstar, which corresponds to the memory to deallocate.

i1 : malloc = foreignFunction("malloc", voidstar, ulong)

o1 = malloc

o1 : ForeignFunction
 
i2 : free = foreignFunction("free", void, voidstar)

o2 = free

o2 : ForeignFunction
 
i3 : finalizer = x -> (print("freeing memory at " | net x); free x)

o3 = finalizer

o3 : FunctionClosure
 
i4 : for i to 9 do (x := malloc 8; registerFinalizer(x, finalizer))
 
i5 : collectGarbage()
freeing memory at 0xffff68071010
freeing memory at 0xffff68070bc0
freeing memory at 0xffff680712c0
freeing memory at 0xffff680712a0
freeing memory at 0xffff68006fa0
freeing memory at 0xffff68070ff0
freeing memory at 0xffff6806f1e0
freeing memory at 0xffff68071300
freeing memory at 0xffff680718d0

See also

Ways to use this method:

The source of this document is in ForeignFunctions.m2:1806:0.