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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 0x7ff9180718e0
freeing memory at 0x7ff9180712b0
freeing memory at 0x7ff918006fc0
freeing memory at 0x7ff918070bd0
freeing memory at 0x7ff91806f1f0
freeing memory at 0x7ff918071310
freeing memory at 0x7ff918071020
freeing memory at 0x7ff9180712d0
freeing memory at 0x7ff918071000

See also

Ways to use this method:


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