extend safe package by finalizers

[Kamil Samigullin]

https://golang.org/pkg/runtime/#SetFinalizer

file, err := safe.OpenFile()
if err ...
// no call defer file.Close()
// panic in runtime

how it works

Open() -> SetFinalizer

Close() -> UnsetFinalizer

[Kamil Samigullin]

also, the custom profiler can be usefull:

Open() -> profile.Add

Close() -> profile.Remove