I'm looking for a function something like writeln or write, but instead of writing to stdout, it writes to a string and returns the string.

So i would like something like:

import std.stdio;
import std.conv;

string write_to_string(T...)(T values ) {
  string s;
  foreach ( value; values ) s ~= to!string( value );
  return s;
}

But because this is such a standard type of thing to do, i'd like to use whatever the standard function is for doing it, if there is one.

So . . . is there one?  Like maybe some way to dress a string up as a file and pass it through the usual write/writeln apparatus?  My only real requirement is that it be something really easy to do.

Thanks in advance for any pointers.

dan

On Sat, May 02, 2020 at 02:22:42AM +0000, dan via Digitalmars-d-learn wrote:
> I'm looking for a function something like writeln or write, but instead of writing to stdout, it writes to a string and returns the string.
[...]

	import std.format : format;
	string str = format("%s %s %s", obj1, obj2, obj3);


T

-- 
Once bitten, twice cry...

On Saturday, 2 May 2020 at 02:29:43 UTC, H. S. Teoh wrote:
> On Sat, May 02, 2020 at 02:22:42AM +0000, dan via Digitalmars-d-learn wrote:
>> I'm looking for a function something like writeln or write, but instead of writing to stdout, it writes to a string and returns the string.
> [...]
>
> 	import std.format : format;
> 	string str = format("%s %s %s", obj1, obj2, obj3);
>
>
> T

Thanks HS!

That looks like a good move, if format will do the string conversion for me.

But one thing that would be troublesome is that i would have to make sure to count up the %s so that they match the number of arguments.  I would like to do without that, just like writeln does.

Anyhow, though, thanks for point out format.

dan

On 5/1/20 10:40 PM, dan wrote:
> On Saturday, 2 May 2020 at 02:29:43 UTC, H. S. Teoh wrote:
>> On Sat, May 02, 2020 at 02:22:42AM +0000, dan via Digitalmars-d-learn wrote:
>>> I'm looking for a function something like writeln or write, but instead of writing to stdout, it writes to a string and returns the string.
>> [...]
>>
>>     import std.format : format;
>>     string str = format("%s %s %s", obj1, obj2, obj3);
>>
>>
>> T
> 
> Thanks HS!
> 
> That looks like a good move, if format will do the string conversion for me.
> 
> But one thing that would be troublesome is that i would have to make sure to count up the %s so that they match the number of arguments.  I would like to do without that, just like writeln does.

import std.conv: text;

string str = text(obj1, " ", obj2, " ", obj3);

-Steve

On Saturday, 2 May 2020 at 02:49:04 UTC, Steven Schveighoffer wrote:
> On 5/1/20 10:40 PM, dan wrote:
>> On Saturday, 2 May 2020 at 02:29:43 UTC, H. S. Teoh wrote:
>>> On Sat, May 02, 2020 at 02:22:42AM +0000, dan via Digitalmars-d-learn wrote:
>>>> [...]
>>> [...]
>>>
>>>     import std.format : format;
>>>     string str = format("%s %s %s", obj1, obj2, obj3);
>>>
>>>
>>> T
>> 
>> Thanks HS!
>> 
>> That looks like a good move, if format will do the string conversion for me.
>> 
>> But one thing that would be troublesome is that i would have to make sure to count up the %s so that they match the number of arguments.  I would like to do without that, just like writeln does.
>
> import std.conv: text;
>
> string str = text(obj1, " ", obj2, " ", obj3);
>
> -Steve

Awesome, thanks Steve.  That's perfect.  So the function i was looking for was text (or, i guess, std.conv.text).

dan

On 5/1/20 7:40 PM, dan wrote:> On Saturday, 2 May 2020 at 02:29:43 UTC, H. S. Teoh wrote:
>> On Sat, May 02, 2020 at 02:22:42AM +0000, dan via Digitalmars-d-learn
>> wrote:
>>> I'm looking for a function something like writeln or write, but
>>> instead of writing to stdout, it writes to a string and returns the
>>> string.
>> [...]
>>
>>     import std.format : format;
>>     string str = format("%s %s %s", obj1, obj2, obj3);
>>
>>
>> T
>
> Thanks HS!
>
> That looks like a good move, if format will do the string conversion for
> me.
>
> But one thing that would be troublesome is that i would have to make
> sure to count up the %s so that they match the number of arguments.  I
> would like to do without that, just like writeln does.

If you can live with a mildly awkward way of passing it, format() can take the format string at compile time as well:

  string str = format!"%s %s %s"(obj1, obj2, obj3);

You get a compilation error if format specifications don't match the arguments. (There are bug reports about that check but it mostly works great.)

Ali

On Saturday, 2 May 2020 at 10:36:47 UTC, Ali Çehreli wrote:
> On 5/1/20 7:40 PM, dan wrote:> On Saturday, 2 May 2020 at 02:29:43 UTC, H. S. Teoh wrote:
> >> On Sat, May 02, 2020 at 02:22:42AM +0000, dan via
> Digitalmars-d-learn
> >> wrote:
> >>> I'm looking for a function something like writeln or write,
> but
> >>> instead of writing to stdout, it writes to a string and
> returns the
> >>> string.
> >> [...]
> >>
> >>     import std.format : format;
> >>     string str = format("%s %s %s", obj1, obj2, obj3);
> >>
> >>
> >> T
> >
> > Thanks HS!
> >
> > That looks like a good move, if format will do the string
> conversion for
> > me.
> >
> > But one thing that would be troublesome is that i would have
> to make
> > sure to count up the %s so that they match the number of
> arguments.  I
> > would like to do without that, just like writeln does.
>
> If you can live with a mildly awkward way of passing it, format() can take the format string at compile time as well:
>
>   string str = format!"%s %s %s"(obj1, obj2, obj3);
>
> You get a compilation error if format specifications don't match the arguments. (There are bug reports about that check but it mostly works great.)
>
> Ali

Thanks Ali.

That's also a good point, and would remove one of my qualms about all of the %s reps.

So if for any reason i cannot use the text function (or if i want to double check on the types of the objects) this would be a good thing to use.

dan