Meador Inge schrieb:
Recently some discussion began in the issue 3132 thread ( http://bugs.python.org/issue3132) regarding implementation of the new struct string syntax for PEP 3118. Mark Dickinson suggested that I bring the discussion on over to Python Dev. Below is a summary of the questions\comments from the thread.
Unpacking a long-double
- Should this return a Decimal object or a ctypes 'long double'?
- Using ctypes 'long double' is easier to implement, but precision is lost when needing to do arithmetic, since the value for cytpes 'long
double' is converted to a Python float. 3. Using Decimal keeps the desired precision, but the implementation would be non-trivial and architecture specific (unless we just picked a fixed number of bytes regardless of the architecture). 4. What representation should be used for standard size and alignment? IEEE 754 extended double precision?
A variant of 2. would be to unpack into a ctypes 'long double', and extend the ctypes 'long double' type to retrive the value as Decimal instance, in addition to the default conversion into a Python float.