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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 0xff6830083c80
freeing memory at 0xff6830083c60
freeing memory at 0xff6830083d00
freeing memory at 0xff6830083cc0
freeing memory at 0xff68300834e0
freeing memory at 0xff6830083500
freeing memory at 0xff6830083ce0
freeing memory at 0xff6830083c40
freeing memory at 0xff6830083ca0

See also

Ways to use this method:

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