Re: Using output-range overloads of SysTime.toISO{Ext}String with formatting code
On Tuesday, 9 July 2019 at 08:51:59 UTC, Mitacha wrote:
I've managed to make it work using 'alias this' and wrapper
struct.
https://run.dlang.io/is/3SMEFZ
It's not an elegant solution, there could be a better way to do
this.
Yea, a wrapper struct with custom `toString` seems the most
obvious way forward. No need to bother with `alias this`,
though, since one only needs the wrapper struct at the point
where one wants to format the datetime info. A wrapper struct
like this:
struct ISOExtSysTime
{
private SysTime systime;
public void toString (Output) (ref Output output)
if (isOutputRange!(Output, char))
{
this.systime.toISOExtString(output);
}
}
allows easy usage along the lines of:
writefln!"%s"(ISOExtSysTime(sys_time));
... and one could easily write a small factory function to
shorten the code if needed.
Re: Using output-range overloads of SysTime.toISO{Ext}String with formatting code
On Monday, 8 July 2019 at 12:53:18 UTC, Digital Mars wrote: I guess that there is no way to have `writeln` automatically use the output range overload instead of allocating one. You need somehow to provide the output range to `toISOExtString` explicitly because `writeln` outputs the return of `toISOExtString` and have no ability to use specific overload. That is compiler calls `toISOExtString` and then passes its return to `writeln`. Probably library solution isn't possible in this case. Workaround is using own wrapper to provide output range to `toISOExtString`. This is pretty much what I'd concluded myself, but I wanted to check to make sure there wasn't some clever option I didn't know about. A helper function with wrapper struct seems the obvious way forward.
Using output-range overloads of SysTime.toISO{Ext}String with formatting code
On Monday, 8 July 2019 at 12:53:18 UTC, Digital Mars wrote: 08.07.2019 13:38, Joseph Rushton Wakeling пишет: [...] Sorry that my answer wasn't thoughtful. I guess that there is no way to have `writeln` automatically use the output range overload instead of allocating one. You need somehow to provide the output range to `toISOExtString` explicitly because `writeln` outputs the return of `toISOExtString` and have no ability to use specific overload. That is compiler calls `toISOExtString` and then passes its return to `writeln`. Probably library solution isn't possible in this case. Workaround is using own wrapper to provide output range to `toISOExtString`. I've managed to make it work using 'alias this' and wrapper struct. https://run.dlang.io/is/3SMEFZ It's not an elegant solution, there could be a better way to do this.
Re: Using output-range overloads of SysTime.toISO{Ext}String with formatting code
08.07.2019 13:38, Joseph Rushton Wakeling пишет: Thanks for taking the time to answer, but I don't think this really addresses my question. Your example shows a struct with `toString` overloads. However, SysTime.toISOExtString does not work like this: it is a method with two explicit overloads, one of which just returns a newly allocated `string`, the other of which returns nothing but accepts an output range as input: https://dlang.org/phobos/std_datetime_systime.html#.SysTime.toISOExtString I want to know if there's an easy way to work with that in `format` and `writefln` statements. Note that while SysTime does also have `toString` methods, these give no control over the kind of datetime string that results: https://dlang.org/phobos/std_datetime_systime.html#.SysTime.toString Since I explicitly need the extended ISO format, I need to use `toISOExtString` directly. Sorry that my answer wasn't thoughtful. I guess that there is no way to have `writeln` automatically use the output range overload instead of allocating one. You need somehow to provide the output range to `toISOExtString` explicitly because `writeln` outputs the return of `toISOExtString` and have no ability to use specific overload. That is compiler calls `toISOExtString` and then passes its return to `writeln`. Probably library solution isn't possible in this case. Workaround is using own wrapper to provide output range to `toISOExtString`.
Re: Using output-range overloads of SysTime.toISO{Ext}String with formatting code
On Sunday, 7 July 2019 at 20:12:30 UTC, drug wrote: 07.07.2019 17:49, Joseph Rushton Wakeling пишет: it's possible to do something like `writefln!"%s"(now.toISOExtString)` and have it automatically use the output range overload rather than allocating a new string instance. This is exactly how it is intended to work: https://run.dlang.io/is/ATjAkx Thanks for taking the time to answer, but I don't think this really addresses my question. Your example shows a struct with `toString` overloads. However, SysTime.toISOExtString does not work like this: it is a method with two explicit overloads, one of which just returns a newly allocated `string`, the other of which returns nothing but accepts an output range as input: https://dlang.org/phobos/std_datetime_systime.html#.SysTime.toISOExtString I want to know if there's an easy way to work with that in `format` and `writefln` statements. Note that while SysTime does also have `toString` methods, these give no control over the kind of datetime string that results: https://dlang.org/phobos/std_datetime_systime.html#.SysTime.toString Since I explicitly need the extended ISO format, I need to use `toISOExtString` directly.
Re: Using output-range overloads of SysTime.toISO{Ext}String with formatting code
07.07.2019 17:49, Joseph Rushton Wakeling пишет: it's possible to do something like `writefln!"%s"(now.toISOExtString)` and have it automatically use the output range overload rather than allocating a new string instance. This is exactly how it is intended to work: https://run.dlang.io/is/ATjAkx
Using output-range overloads of SysTime.toISO{Ext}String with formatting code
Hello folks, Is there an idiomatic/intended way to use the output-range taking overloads of SysTime.toISOString and toISOExtString with stuff like `writeln` and `format`, as opposed to explicitly generating an output range to stdout or a string, and passing that to these methods? I'm a bit unfamiliar with exactly all the ins and outs of the more recent output-range-based formatting design, but what I'm interested in whether it's possible to do something like `writefln!"%s"(now.toISOExtString)` and have it automatically use the output range overload rather than allocating a new string instance. If that exact syntax doesn't work, is there anything almost as convenient? Thanks & best wishes, -- Joe
