[Python-Dev] Mixing float and Decimal -- thread reboot (original) (raw)

Guido van Rossum guido at python.org
Wed Mar 24 22:09:59 CET 2010

W00t!

On Wed, Mar 24, 2010 at 1:56 PM, Raymond Hettinger <raymond.hettinger at gmail.com> wrote:

FWIW, my viewpoint on this is softening over time and I no longer feel a need to push for a new context flag.

It is probably simplest for users if implicit coercions didn't come with control knobs.  We already have Fraction+float-->float occurring without any exceptions or warnings, and nothing bad has happened as a result. Also, I'm reminded of Tim Peter's admonition to resist extending the decimal spec. I used to worry that any decimal/float interactions were most likely errors and shouldn't pass silently.  Now, I've just stopped worrying and I feel better already ;-) Adding a FAQ entry is simpler than building-out Context object circuitry and documenting it in an understandable way. Raymond

On Mar 24, 2010, at 12:36 PM, Stefan Krah wrote: Nick Coghlan <ncoghlan at gmail.com> wrote: Raymond Hettinger wrote: The decimal module is already drowning in complexity, so it would be best to keep it simple:  one boolean flag that if set would warn about any implicit decimal/float interaction.

Agreed - those that want exceptions instead can use the usual warnings module mechanisms to trigger them. I'm not sure about the warnings module. If lower complexity is a goal, I would prefer Facundo's original proposal of just adding a single new signal. Users who just want to know if a NonIntegerConversion has occurred can check the flags, users who want an exception set the trap. With the warnings module, users have to know (and deal with) two exception handling/suppressing mechanisms. Stefan Krah

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-- --Guido van Rossum (python.org/~guido)

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