Hans Åberg wrote: > > I don't think so. I think I was due to the implementation in C where > > dynamic data structures are much more effort to write. Otherwise > > it's better to let the programs use as much memory as they can (by > > system limits, ulimit, etc.) and not impose arbitrary limits. > > But the C parser has had dynamic allocations up to the limit as far as I > recall, the 1990s. And there are POSIX specs for YACC.
I don't understand why they did that. They even say "memory exhausted" which is probably wrong in most cases. (There's enough memory available, the parser just chooses not to use it.) As the bash example shows, such arbitrary limits keep hitting users many years after (just like the Y2K bug), so it's better to avoid them from the start (like the C++ parsers do). > It the past double indirection was considered slow, but today it is best to > test the specific application. Testing performance in a meaningful way is very difficult, today more than ever, especially if memory access is involved. Small changes in the problem size might have a big effect due to cache misses etc. What's fast on one machine might be slow on the next one. Do you want to optimize for best case, worst case, or average performance? Very few people have the ability to make good judgement here or the means (different machines) and time available to do relevant tests. Regards, Frank
