std.format with wstring and dstring

22 hours ago

Robert Schadek

21 hours ago

monkyyy

15 hours ago

Robert Schadek

9 hours ago

Richard (Rikki) Andrew Cattermole

1 hour ago

IchorDev

1 hour ago

Dom DiSc

I spend one day at dconf this year and removed wstring and dstring support from
std.format to improve compile speed. std.format.FormatSpec is no longer a template
on the character type, and the bitfield template was removed as well.

The dub package can be found here https://code.dlang.org/packages/std2_format
https://github.com/burner/std2.format

When compiling the below format call with ldc and -ftime-trace

import std2.format;
//import std.format;

void main(){
    string s = format("Hello %s %s %.2f", "World", 1337, 13.37);
    assert(s == "Hello World 1337 13.37", s);
}

The overall compile time decreases from 290ms to 223ms and the frontend time for
the format call goes from 71ms to 23ms.

Currently, alias this and toString tests fail. And I can't really figure out why.
Also some float tests fails.

PR's are always welcome.

Meta: Removing wstring and dstring support from std.format for phobos 3 should be looked at IMHO.

21 hours ago

Re: std.format with wstring and dstring

Posted by monkyyy
in reply to Robert Schadek

Permalink

monkyyy

Posted in reply to Robert Schadek

Permalink

On Sunday, 7 September 2025 at 12:29:08 UTC, Robert Schadek wrote:

The dub package can be found here https://code.dlang.org/packages/std2_format
https://github.com/burner/std2.format

When compiling the below format call with ldc and -ftime-trace

import std2.format;
//import std.format;

void main(){
    string s = format("Hello %s %s %.2f", "World", 1337, 13.37);
    assert(s == "Hello World 1337 13.37", s);
}

The overall compile time decreases from 290ms to 223ms and the frontend time for
the format call goes from 71ms to 23ms.

Currently, alias this and toString tests fail. And I can't really figure out why.
Also some float tests fails.

PR's are always welcome.

Meta: Removing wstring and dstring support from std.format for phobos 3 should be looked at IMHO.

wouldnt be far faster to just rip out all the c api complexity and just do a simple sane api?

std.format is on my list of modules that I want replaced. Its written with a lot of error conditions, rather than just adapting to the inputs. Hence lots of potential for exceptions being thrown that don't need to be. Multiple multipliers in ``formattedWrite``: format string, output range. What I'd like to do is to force IES for one or more values, if you want finer grained control you want do one value a time (``formatValue``). ```d writeln(i"$i ${i:X}: $(j + 1)/${(j + 1):X} $1 ${0:X}", k, obj, "atend"); ``` Require the use of a string builder, rather than any old output range. This is a required change for pretty printing. It requires the use of arbitrary inserts and removals that ranges can't do. Every template parameter like these that you have is a multiplier of instances, and that isn't good for compile times. Simplifying them down may seem like a pain, but it helps quite significantly. Given that there are some clear requirements and use cases we can in fact simplify it without hurting anyone enough to care.

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