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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 0xffbcc00836e0
freeing memory at 0xffbcc0083d80
freeing memory at 0xffbcc0083da0
freeing memory at 0xffbcc0083dc0
freeing memory at 0xffbcc0083e20
freeing memory at 0xffbcc0083e40
freeing memory at 0xffbcc0083e00
freeing memory at 0xffbcc0083de0
freeing memory at 0xffbcc00836c0

See also

Ways to use this method:

The source of this document is in ForeignFunctions.m2:1818:0.