A long time ago, I wrote some stuff on how generators are not lists (okay, technically it was about iterators), andone of the things that I mentioned is that generators do not havelist methods. Well, there's a consequence of that that only struck merecently: you need completely different code to modify a returnedgenerator than to modify a returned list .

Suppose you have a function that returns something that is conceptuallya list of items. Further suppose that you have another function thatmodifies what

There is a fashion in monitoring systems that, once you have one, youstart monitoring and alerting on everything that you possibly can thinkof, no matter what it is. If you can measure it, you do, and when itgets too big or too small your system lets people know about it.

This is, by and large, a mistake.

It is a mistake because you've created a system that isn't actually(usefully) informative, just noisy. What your monitoring system shouldbe

Here is an obvious yet important thing:

When you make decisions between the costs of development and the costsof operation , it is quite important to get theactual costs right (on both sides); otherwise you will be balancingthings based on bad data, which usually doesn't end well. One would liketo think that this is easy, but in fact there has usually been a lot ofmythology about these costs floating around (I suspect especially sowhen the actual costs are changing rapidly).

The classical