Jonathan Gardner wrote:
Let me share my personal insight. I used Python for a mission-critical application that needed, in effect, almost 100% uptime with superior throughput. In other words, it was a very fine piece of art that needed to be precise and correct. In the end, Python delivered, under budget, under schedule, and with superbly low maintenance costs (practically 0 compared to other systems written in Java and C). I didn't have to use any of the features you mentioned, and I can't imagine why you would need them. In fact, having them in the language would encourage others to use them and make my software less reliable.
At the risk of prolonging this thread, I'll add my own personal insight. I've spent a decent amount of time programming in Java, and the overhead of assigning a too-restrictive privacy level (which happens a lot, once privacy levels are in the language) has cost me an immense amount of time. I've lost count of how often I've had a software package which made an element non-public, in many cases for no apparent good reason, except that they hadn't anticipated the way I was going to use their code. Tracing down the consequences of these decisions, and trying to work around them, has been exceptionally time-consuming for me. You can say that I can go and modify the source code, as long as I have the source code, but that misses the point: I don't WANT to keep my own copy of the code, with the attended overhead in merging it with subsequent releases, etc.
I'm not going to claim that data hiding has no purpose - it clearly addresses a set of concerns that programmers have about managing APIs. But I've found that its difficulties far outweigh its benefits.
Sam Bayer -- http://mail.python.org/mailman/listinfo/python-list
