• vladde (5/7) Aug 15 2015 I made a PR to phobos where I modified `std.format.format`.
• cym13 (4/11) Aug 15 2015 I think it has to do with the fact that string is an alias to
• cym13 (24/38) Aug 15 2015 I phrased it completely wrong, an example will be better :
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (18/45) Aug 15 2015 That's actually correct (for reference types). As long as there is no
• Timon Gehr (2/9) Aug 15 2015 Get rid of the 'in' in format's signature.
• Timon Gehr (4/16) Aug 15 2015 Oh, I see, this is by design (which I don't like, but OK.)

"vladde" <v vladde.net> writes:

I made a PR to phobos where I modified `std.format.format`. 
https://github.com/D-Programming-Language/phobos/pull/3528

However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert 
 expression (format("s = %s", s)) of type char[] to string

The line which fails is `p = std.string.format("s = %s", s);`

I don't understand why I can't convert a char[] to string.

"cym13" <cpicard openmailbox.org> writes:

On Saturday, 15 August 2015 at 11:25:20 UTC, vladde wrote:
 I made a PR to phobos where I modified `std.format.format`. 
 https://github.com/D-Programming-Language/phobos/pull/3528

 However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert 
 expression (format("s = %s", s)) of type char[] to string

 The line which fails is `p = std.string.format("s = %s", s);`

 I don't understand why I can't convert a char[] to string.

I think it has to do with the fact that string is an alias to   
immutable(char)[]   and you can't implicitely cast an immutable 
to a regular variable.

"cym13" <cpicard openmailbox.org> writes:

On Saturday, 15 August 2015 at 11:34:01 UTC, cym13 wrote:
 On Saturday, 15 August 2015 at 11:25:20 UTC, vladde wrote:
 I made a PR to phobos where I modified `std.format.format`. 
 https://github.com/D-Programming-Language/phobos/pull/3528

 However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert 
 expression (format("s = %s", s)) of type char[] to string

 The line which fails is `p = std.string.format("s = %s", s);`

 I don't understand why I can't convert a char[] to string.

 I think it has to do with the fact that string is an alias to   
 immutable(char)[]   and you can't implicitely cast an immutable 
 to a regular variable.

I phrased it completely wrong, an example will be better :

     import std.stdio;

     void fun(immutable(int)[] i) {
         i.writeln();
     }

     void main() {
         int[] i = [42];
         fun(i);
     }

Will not compile because there is no certainty that fun() won't
change the array while the following will work

     import std.stdio;

     void fun(immutable(int)[] i) {
         i.writeln();
     }

     void main() {
         int[] i = [42];
         fun(i.dup);

         immutable(int)[] j = [42];
         fun(j);

         immutable(int[]) k = [42];
         fun(k);
     }

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 08/15/2015 04:45 AM, cym13 wrote:

 On Saturday, 15 August 2015 at 11:34:01 UTC, cym13 wrote:
 On Saturday, 15 August 2015 at 11:25:20 UTC, vladde wrote:
 I made a PR to phobos where I modified `std.format.format`.
 https://github.com/D-Programming-Language/phobos/pull/3528

 However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert expression
 (format("s = %s", s)) of type char[] to string

 The line which fails is `p = std.string.format("s = %s", s);`

 I don't understand why I can't convert a char[] to string.

 I think it has to do with the fact that string is an alias to
 immutable(char)[]   and you can't implicitely cast an immutable to a
 regular variable.


That's actually correct (for reference types). As long as there is no 
indirection, a value type can be casted implicitly:

struct S
{
     int i;
}

void main()
{
     auto i = immutable(S)();
     auto m = S();

     m = i;    // copied; fine
}

 I phrased it completely wrong, an example will be better :

      import std.stdio;

      void fun(immutable(int)[] i) {
          i.writeln();
      }

      void main() {
          int[] i = [42];
          fun(i);
      }

 Will not compile because there is no certainty that fun() won't
 change the array

Actually, that's the job of 'const'. Here, it is not fun's ability to 
mutate but the caller's. 'immutable' on a function interface means a 
requirement: The caller *must* provide immutable data so that the 
function can rely on it not being changed by anyone.

Ali

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/15/2015 01:25 PM, vladde wrote:
 I made a PR to phobos where I modified `std.format.format`.
 https://github.com/D-Programming-Language/phobos/pull/3528

 However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert expression
 (format("s = %s", s)) of type char[] to string

 The line which fails is `p = std.string.format("s = %s", s);`

 I don't understand why I can't convert a char[] to string.

Get rid of the 'in' in format's signature.

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/15/2015 01:54 PM, Timon Gehr wrote:
 On 08/15/2015 01:25 PM, vladde wrote:
 I made a PR to phobos where I modified `std.format.format`.
 https://github.com/D-Programming-Language/phobos/pull/3528

 However the auto builder fails, with the error message:
 runnable/test23.d(1219): Error: cannot implicitly convert expression
 (format("s = %s", s)) of type char[] to string

 The line which fails is `p = std.string.format("s = %s", s);`

 I don't understand why I can't convert a char[] to string.

 Get rid of the 'in' in format's signature.

Oh, I see, this is by design (which I don't like, but OK.)
The reason the conversion does not go through is that format is not 
marked as pure.