On Mon, 04 Jul 2005 21:17:21 +0200, tiissa wrote: > Josiah Manson wrote: >> Hello. I am very new to Python, and have been unable to figure out how >> to check if a variable exists or not. In the following code I have made >> a kludge that works, but I think that it would be clearer to check if >> closest exists and not have to initialize it in the first place. How is >> that check done? > > Variables are stored in two dictionnaries: globals() (for global > variables) and locals() (for the local ones, which are also global on > top level).
Should we *really* be encouraging newbies to mess with globals() and locals()? Isn't that giving them the tools to shoot their foot off before teaching them how to put shoes on? [snip] >> I also have a few other questions to tack on if you don't mind. I >> am >> setting dist to 1e9, because that is a larger value than any of the >> places in the galaxy will be far away. Is there a better way to >> initialize dist so that it is impossible for this to fail? For example, >> would setting dist to infinity work, and how is that done? > > The float constructed from the string 'inf', float('inf'), may do the > trick. I don't know the details, though. > > >>> 1e100 < float('inf') > True This is not guaranteed to work in any Python. It *might* work, depending on the underlying C library, which is operating system dependent. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list