Re: FormatSpec struct
On Friday, 13 April 2012 at 09:10:37 UTC, James Miller wrote: 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
Re: FormatSpec struct
* James Miller [2012-04-13 19:16:48 +1200]: > * Paul D. Anderson > [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
* Paul D. Anderson [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
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
