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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 0x7ff7f0070f20
freeing memory at 0x7ff7f0070a70
freeing memory at 0x7ff7f00024e0
freeing memory at 0x7ff7f0070620
freeing memory at 0x7ff7f0061670
freeing memory at 0x7ff7f000a040
freeing memory at 0x7ff7f006d560
freeing memory at 0x7ff7f006d540
freeing memory at 0x7ff7f0070640
freeing memory at 0x7ff7f00711b0

See also

Ways to use this method:


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