[issue7754] decimal.Decimal 0.0**0.0 error

[Mark Dickinson]

Mark Dickinson <dickinsm at gmail.com> added the comment:

Now that I think about it, this could be 'fixed' without breaking compliance:  all the specification requires is that a power function with the specified behaviour is present *somewhere* in the decimal module;  it needn't be linked to the ** operator.  So there could be two versions of power in decimal.py:  one version (called Decimal.power) that strictly conforms to the specification, and another (Decimal.__pow__) that's identical in every way except that it returns Decimal('1') for Decimal('0.0')**0.

While we're at it, we could also 'fix' Decimal.__pos__ and Decimal.__neg__ similarly:  the standard requires operations 'plus' and 'minus', with the slightly surprising (to me, at least) properties that plus(-0.0) = 0.0 and minus(0.0) = 0.0  (for both these, -0.0 seems more natural);  but there's no requirement that Python's __pos__ and __neg__ be identical to these.

But these changes would come with all the usual costs: extra code, tests and documentation, future maintenance costs, possibility of introducing bugs, user confusion, possible backwards compatibility issues,...  So there would have to be some significant perceived benefits to outweigh the costs.

Perhaps a discussion on the python-dev mailing list would be in order?

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status: pending -> open

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue7754>
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