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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 0x7efdbc06a430
freeing memory at 0x7efdbc0705c0
freeing memory at 0x7efdbc0705e0
freeing memory at 0x7efdbc071f40
freeing memory at 0x7efdbc071f20
freeing memory at 0x7efdbc065e50
freeing memory at 0x7efdbc06a620
freeing memory at 0x7efdbc0708a0
freeing memory at 0x7efdbc004b00
freeing memory at 0x7efdbc070190

See also

Ways to use this method:


The source of this document is in /build/reproducible-path/macaulay2-1.25.05+ds/M2/Macaulay2/packages/ForeignFunctions.m2:1806:0.