Op 2005-08-29, Steve Holden schreef <[EMAIL PROTECTED]>: > Antoon Pardon wrote: >> Op 2005-08-27, Steve Holden schreef <[EMAIL PROTECTED]>: >> >>>> >>>If you want an exception from your code when 'w' isn't in the string you >>>should consider using index() rather than find. >> >> >> Sometimes it is convenient to have the exception thrown at a later >> time. >> >> >>>Otherwise, whatever find() returns you will have to have an "if" in >>>there to handle the not-found case. >> >> >> And maybe the more convenient place for this "if" is in a whole different >> part of your program, a part where using -1 as an invalid index isn't >> at all obvious. >> >> >>>This just sounds like whining to me. If you want to catch errors, use a >>>function that will raise an exception rather than relying on the >>>invalidity of the result. >> >> >> You always seem to look at such things in a very narrow scope. You never >> seem to consider that various parts of a program have to work together. >> > Or perhaps it's just that I try not to mix parts inappropriately.
I didn't know it was inappropriately to mix certain parts. Can you give a list of modules in the standard list I shouldn't mix. >> So what happens if you have a module that is collecting string-index >> pair, colleted from various other parts. In one part you >> want to select the last letter, so you pythonically choose -1 as >> index. In an other part you get a result of find and are happy >> with -1 as an indictation for an invalid index. Then these >> data meet. >> > That's when debugging has to start. Mixing data of such types is > somewhat inadvisable, don't you agree? The type of both data is the same, it is a string-index pair in both cases. The problem is that a module from the standard lib uses a certain value to indicate an illegal index, that has a very legal value in python in general. > I suppose I can't deny that people do things like that, myself included, It is not about what people do. If this was about someone implementing find himself and using -1 as an illegal index, I would certainly agree that it was inadvisable to do so. Yet when this is what python with its libary offers the programmer, you seem reluctant find fault with it. > but mixing data sets where -1 is variously an error flag and a valid > index is only going to lead to trouble when the combined data is used. Yet this is what python does. Using -1 variously as an error flag and a valid index and when people complain about that, you say it sounds like whining. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
