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Packages » ForeignFunctions :: registerFinalizer(ForeignObject,Function)
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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 0x7f2dcc05e150
freeing memory at 0x7f2dcc0521e0
freeing memory at 0x7f2dcc068150
freeing memory at 0x7f2dcc066810
freeing memory at 0x7f2dcc066830
freeing memory at 0x7f2dcc0688a0
freeing memory at 0x7f2dcc0687f0
freeing memory at 0x7f2dcc068880
freeing memory at 0x7f2dcc004f20

Ways to use this method: