Re: FormatSpec struct
* Paul D. Anderson paul.d.removethis.ander...@comcast.andthis.net [2012-04-13 07:50:31 +0200]: I'm trying to add formatted output to my decimal arithmetic module. Decimals should format like floating point, using 'E', 'F' and 'G', etc. I would expect a format string like %9.6e to parse as width = 9, precision = 6, using exponential notation. In std.format there is a FormatSpec struct that looks as if it will do the parsing for me. As far as I can tell the usage is: auto spec = std.format.FormatSpec!char(9.6e); writeln(fmtspec = , fmtspec); But it doesn't do what I think it should do. The output of the method is: fmtspec = address = 1637116 width = 0 precision = 2147483646 spec = s indexStart = 0 indexEnd = 0 flDash = false flZero = false flSpace = false flPlus = false flHash = false nested = trailing = 9.6e The width field should be 9, the precision field should be 6, and the spec field should be 'e'. Instead it seems to disregard the input string and return a default FormatSpec, with only the 'trailing' field populated, containing the input. What am I missing here? I've tried variations -- %9.6e, s, %s, etc, but the input is always relegated to the trailing field. Paul Hey Paul, so some investigation has led me to believe that FormatSpec is really just for internal usage. The documentation is a bit misleading (to the point of being possibly completely false). FormatSpec, AFAICT, is essentially just a parser for the standard format specifier, but its not very clear as to proper usage. I'm going to try to improve it and submit a pull request, until then looking at the source code for std.format should give you some idea of how to best use it. -- James Miller
Re: FormatSpec struct
* James Miller ja...@aatch.net [2012-04-13 19:16:48 +1200]: * Paul D. Anderson paul.d.removethis.ander...@comcast.andthis.net [2012-04-13 07:50:31 +0200]: I'm trying to add formatted output to my decimal arithmetic module. Decimals should format like floating point, using 'E', 'F' and 'G', etc. I would expect a format string like %9.6e to parse as width = 9, precision = 6, using exponential notation. Hey Paul, so some investigation has led me to believe that FormatSpec is really just for internal usage. The documentation is a bit misleading (to the point of being possibly completely false). FormatSpec, AFAICT, is essentially just a parser for the standard format specifier, but its not very clear as to proper usage. I'm going to try to improve it and submit a pull request, until then looking at the source code for std.format should give you some idea of how to best use it. -- James Miller So I made the pull request, the documentation you need to read is here: https://github.com/Aatch/phobos/commit/cda3c079ee32d98a017f88949c10097840baa075 Hopefully it helps. -- James Miller
Re: FormatSpec struct
On Friday, 13 April 2012 at 09:10:37 UTC, James Miller wrote: snip/ So I made the pull request, the documentation you need to read is here: https://github.com/Aatch/phobos/commit/cda3c079ee32d98a017f88949c10097840baa075 Hopefully it helps. -- James Miller Thanks. That did the trick. Paul
FormatSpec struct
I'm trying to add formatted output to my decimal arithmetic module. Decimals should format like floating point, using 'E', 'F' and 'G', etc. I would expect a format string like %9.6e to parse as width = 9, precision = 6, using exponential notation. In std.format there is a FormatSpec struct that looks as if it will do the parsing for me. As far as I can tell the usage is: auto spec = std.format.FormatSpec!char(9.6e); writeln(fmtspec = , fmtspec); But it doesn't do what I think it should do. The output of the method is: fmtspec = address = 1637116 width = 0 precision = 2147483646 spec = s indexStart = 0 indexEnd = 0 flDash = false flZero = false flSpace = false flPlus = false flHash = false nested = trailing = 9.6e The width field should be 9, the precision field should be 6, and the spec field should be 'e'. Instead it seems to disregard the input string and return a default FormatSpec, with only the 'trailing' field populated, containing the input. What am I missing here? I've tried variations -- %9.6e, s, %s, etc, but the input is always relegated to the trailing field. Paul
