[Python-Dev] PEP, take 2: Exception Reorganization for Python 3.0

Raymond Hettinger raymond.hettinger at verizon.net
Fri Aug 5 20:01:26 CEST 2005

Also strong -1 on renaming RuntimeWarning to SemanticsWarning.

Besides being another unnecessary change (trying to solve a non-existent
problem), this isn't an improvement.  The phrase RuntimeWarning is
sufficiently generic to allow it to be used for a number of purposes.
In costrast, SemanticsWarning is less flexible.  Worse, it is not at all
clear what a Semantics Warning would mean -- it suggests something much
more ominous and complicated that it should.

Another risk from gratuitous changes is the risk of unexpectedly
introducing new problems.  In this case, I find myself remembering the
name as SemanticWarning instead of SemanticsWarning.  These kind of
changes suck -- they fail to take advantage of 15 years of field testing
and risk introducing hard-to-change usability problems.

Likewise, am a strong -1 on renaming RuntimeError to UserError.  The
latter name has some virtues but it is also misread as the User doing
something wrong -- that is definitely not the intended meaning.  While
RuntimeError is a less than perfect name, it should not be changed
unless we have both 1) demonstrated that real world problems have
occurred with the current name and 2) that we have a clearly superior
alternative name (a test which UserError fails).  The only virtue to the
name, UserError, is its symmetry with UserWarning.

-0 on renaming ReferenceError to WeakReferenceError.  The new name does
better suggest the cause.  OTOH, the context of the traceback would also
make that perfectly clear.  I'm not aware of a single user having had a
problem with the current name.  In general, we've avoided long names in
favor of the short and pithy -- the theory was that the only a mnemonic
is needed.  Before adopting this one, there should be some discussion of
1) whether the current name is really that unclear, 2) whether shorter
alternatives would serve (i.e. WeakrefError), and 3) whether the name
suffers from capitalization ambiguity (WeakreferenceError vs

Summary:  Most of the proposed name changes are unnecessary, the new
names are not necessarily better, and there is a high risk of
introducing new usability problems.


More information about the Python-Dev mailing list