Meador Inge schrieb:
Hi All,
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 ===================
1. Should this return a Decimal object or a ctypes 'long double'? 2. 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. -- Thanks, Thomas