On Monday 22 November 2004 18:55, Sven Panne wrote:
Abraham Egnor wrote:
I've found that when writing an interface to a C library that requires resource management, it's much better to use the withX (see Control.Exception.bracket) style of function than to use finalizers - programs are much easier to reason about and debug.
... and have a much more deterministic behaviour regarding resource consumption. This is a very important point which is often forgotten.
Ok, the 'withX' pattern solves both of the problems I mentioned and in addition is more deterministic (and, using bracket, also exception safe). Maybe I should use it instead of finalizers. However, I wonder if it is general enough to be the only method exported from a library. I doubt it, otherwise there would be no 'openFile' and 'hClose' in System.IO but only a 'withFile'. Do you recommend supplying 'newX' and 'freeX' in addition to 'withX'? Or should I rather use 'newX' plus finalizers for those (rare?) cases where 'withX' is not general enough? Ben -- Top level things with identity are evil. -- Lennart Augustsson