Mark Dickinson wrote:
Now that we've got the short float repr in Python, there's less value in having float.__str__ truncate to 12 significant digits (as it currently does). For Python 3.2, I propose making float.__str__ use the same algorithm as float.__repr__ for its output (and similarly for complex).
Apart from simplifying the internals a little bit, one nice feature of this change is that it removes the differences in formatting between printing a float and printing a container of floats:
l = [1/3, 1/5, 1/7] print(l) [0.3333333333333333, 0.2, 0.14285714285714285] print(l[0], l[1], l[2]) 0.333333333333 0.2 0.142857142857
Any thoughts or comments on this?
There's a working patch at http://bugs.python.org/issue9337
Python 2.5.4 (r254:67916, Jan 20 2010, 21:44:03)
float("0.142857142857") * 7 0.99999999999899991 float("0.14285714285714285") * 7 1.0
I've made a number of tools in the past that needed to round-trip a float through a string and back. I was under the impression that floats needed 17 decimal digits to avoid losing precision. How does one do that efficiently if neither str nor repr return 17 digits? Robert Brewer fumanchu@aminus.org