TheFlyingDutchman wrote: >> I explain it by noting that list.index and dict.get serve totally >> different purposes. The former returns the index given a value; the >> latter returns a value given a key. > > And the former raises an exception if the value is not found, while > the latter returns None if the value is not found. > >> There are many areas of poor symmetry in the language and libraries; >> it isn't particularly clever or difficult to find them if one >> looks. Doing so doesn't appear to illustrate any point I see relevant >> in this thread. > > It has been stated in this thread, that in Python, exceptions are used > differently than in other languages. Rather than just use them for > catastrophic errors that can't be dealt with, Python raises exceptions > on routine and survivable situations such as an item not found in a > list. It was mentioned that an exception is more Pythonic than > returning a "not found" value. > > Someone pointed out that find() in str was a contradiction to this > since it doesn't throw an exception but returns a "not found" value, > and the response was that it was believed that find() would be removed > from the language (if so, it does not currently show up on the > "removed list" as has_key() and a few others do - > http://docs.python.org/dev/3.0/whatsnew/3.0.html) and was only there > for "historical reasons". > > I don't believe the poster was trying to illustrate a point already > mentioned in the thread, but to give a contradiction to statements in > the thread. He was asking the question - why doesn't dict.get() throw > an exception on not found if that is the Pythonic way? > > Because it's an explicit short-cut for a frequently-required paradigm. It's effectively an extension to dict indexing - which, you will recall, *does* raise an exception when the key is not found. Does *everything* have to raise such an exception?
There's no requirement for Python to be 100% consistent in its application of a principle, but on the whole it is reasonably consistent. For Pete's sake stop wasting your time and go do some programming. Nothing will ever be perfect, not even Python ;-) regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden --------------- Asciimercial ------------------ Get on the web: Blog, lens and tag the Internet Many services currently offer free registration ----------- Thank You for Reading ------------- -- http://mail.python.org/mailman/listinfo/python-list
