[Python-Dev] various unix platform build/test issues (original) (raw)

M.-A. Lemburg mal@lemburg.com
Thu, 20 Feb 2003 18:59:26 +0100

Tim Peters wrote:

[M.-A. Lemburg]

Isn't that caveat in the complex implementation ? Converting a complex with 0 img part would not cause any loss of information (apart from the usual integer truncations ;-) Hmm. Have you ever met a coercion you didn't like <0.9 wink>?

I'd even coerce strings to floats if possible ;-)

BTW, I implemented that in mxNumber for the fun of it:

from mx.Number import * Float(1.23) + '3.45' 4.67999999999999998223e+0 Rational(2,3) + '3/4' 17/12

Seriously, the above was only meant as hint to not rely on nb_negative for PyNumber_Check(), but to use nb_int for this. After all, code using PyNumber_Check() will expect that at least PyNumber_Int() to work on the object. If you check for nb_negative, this will not always work, since then complex objects would get accepted.

float(complex) also raises an exception unconditionally, and I think for good reasons -- what someone intends by trying to convert a complex number to a float or an int is a mystery. The exceptions raised suggest one plausible intent and how to get at it clearly:

float(1+0j) Traceback (most recent call last): File "", line 1, in ? TypeError: can't convert complex to float; use e.g. abs(z)

I know :-)

-- Marc-Andre Lemburg eGenix.com

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