Finalizer methods called when object is clean out

Finalizer methods are called just the moment before the object is about to be deleted by the garbage collector.

If creating a custom finalize() method for a subclass in a package, then it needs to be exported in the NAMESPACE of that package. If not, it will not be found nor called and there will be no error message.

A finalizer method should never be called explicitly!

# S3 method for class 'Object'
finalize(this, ...)

Arguments

...

Not used.

Author

Henrik Bengtsson

See also

For more information see Object.

Examples

setConstructorS3("MyClass", function() {
  extend(Object(), "MyClass")
})

setMethodS3("finalize", "MyClass", function(this, ...) {
  cat(as.character(this), "is about to be removed from the memory!\n")
})
#> NULL

o <- MyClass()
o <- MyClass()
o <- MyClass()
o <- MyClass()
gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1000385 53.5    1957258 104.6  1957258 104.6
#> Vcells 1822363 14.0    8388608  64.0  3140456  24.0

## MyClass: 0x01BE602C is about to be removed from the memory!
## MyClass: 0x01BFF634 is about to be removed from the memory!
## MyClass: 0x01C13584 is about to be removed from the memory!
##          used (Mb) gc trigger (Mb)
## Ncells 229903  6.2     467875 12.5
## Vcells  53725  0.5     786432  6.0

rm(o)
## MyClass: 0x01C578B0 is about to be removed from the memory!
##          used (Mb) gc trigger (Mb)
## Ncells 229903  6.1     467875 12.3
## Vcells  53725  0.5     786432  6.0