On 25 July 2011 19:47, Raymond Hettinger <raymond.hettinger@gmail.com>wrote:
On Jul 25, 2011, at 1:06 PM, Michael Foord wrote:
Python standard library modules currently using integers for constants:
* re - has flags (OR'able constants) defined in sre_constants, each flag has two names (e.g. re.IGNORECASE and re.I)
What is being proposed here? Will there be a new namespace so that we would start writing re.Flags.IGNORECASE instead of re.IGNORECASE? Are module level constants now going to be considered bad-form?
If constants switch from re.IGNORECASE to re.flags.IGNORECASE, are there any benefits to compensate for being both wordier and slower?
Nope. Just something like this at the module level. IGNORECASE = Flags.IGNORECASE What it gains you is a nicer representation when looking at the values when debugging. On the other hand being able to have access to all the constants namespaced on a single object (as well) doesn't seem like such a bad thing. Michael
* os has SEEK_SET, SEEK_CUR, SEEK_END - **plus** those implemented in posix / nt
Ditto
* doctest has its own flag system, but is really just using integer flags / constants (quite a few of them) * token has a tonne of constants (autogenerated) * socket exports a bunch of constants defined in _socket * gzip has flags: FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT
* errno (builtin module)
EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, EINVAL, ENOTCONN, ESHUTDOWN, EINTR, EISCONN, EBADF, ECONNABORTED
It seems to me that an enum module or class doesn't make any of this code better. AFAICT enums are a fat solution to a thin problem.
Since python makes it so easy to put constants in class namespaces and module namespaces, there is much less need for enums than in statically compiled languages. I think the perceived need is really more of a carry-over coding habit than an actual need.
That being said, this proposal seems to have momentum, so it is going happen anyway. Once introduced, people will think we've endorsed enums as the one right way to code constants, so we will start to see them everywhere. Expect enums to become ubiquitous.
Raymond
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