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ForeignFunctions :: registerFinalizer(ForeignObject,Function)

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

Synopsis

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 0x7fa9bc04f810
freeing memory at 0x7fa9bc04e9a0
freeing memory at 0x7fa9bc04f860
freeing memory at 0x7fa9bc04f1a0
freeing memory at 0x7fa9bc0075b0freeing memory at 0x7fa9bc04f4c0
freeing memory at 0x7fa9bc04f830

freeing memory at 0x7fa9bc04f7a0
freeing memory at 0x7fa9bc048980

Ways to use this method: