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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 0x7f6cc007f930
freeing memory at 0x7f6cc007f990
freeing memory at 0x7f6cc007f9b0
freeing memory at 0x7f6cc007f230
freeing memory at 0x7f6cc007f910
freeing memory at 0x7f6cc007f8f0
freeing memory at 0x7f6cc007f250
freeing memory at 0x7f6cc007f970
freeing memory at 0x7f6cc007f950

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.