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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 0x7f7f1407f910
freeing memory at 0x7f7f1407f930
freeing memory at 0x7f7f1407f950
freeing memory at 0x7f7f1407f990
freeing memory at 0x7f7f1407f250
freeing memory at 0x7f7f1407f230
freeing memory at 0x7f7f1407f9b0
freeing memory at 0x7f7f1407f970
freeing memory at 0x7f7f1407f8f0

See also

Ways to use this method:

The source of this document is in /build/reproducible-path/macaulay2-1.25.11+ds/M2/Macaulay2/packages/ForeignFunctions.m2:1807:0.