Hi, I want to modify or extend std.stdio.writefln in order to support (for example) a String object.. i.e.: I would like to be able to do something like that

String s = new String("Hello World");
writefln(s);

I thought that it should be possible by writing some sort of wrapper around the original writefln which scans the _arguments array and if an argument is a String object it does an in-place substitution of the argument to a standard D string type printable by writefln.

Now let's come to my 2nd question: what are dchar and dstring and their differences from char[] (or wchar[]) ?

Thanks in advance
Lorenzo "Arbiter" Villani

Lorenzo Villani wrote:
> Hi, I want to modify or extend std.stdio.writefln in order to support (for example) a String object.. i.e.: I would like to be able to do something like that
> 
> String s = new String("Hello World");
> writefln(s);
> 
> I thought that it should be possible by writing some sort of wrapper around the original writefln which scans the _arguments array and if an argument is a String object it does an in-place substitution of the argument to a standard D string type printable by writefln.

You just need to define a toString() method for your class, then writefln will automatically call that.

> 
> Now let's come to my 2nd question: what are dchar and dstring and their differences from char[] (or wchar[]) ?

dchar is a 32-bit type, for storing a UTF-32 code unit.  dstring is an array of dchar, in other words a UTF-32 string.  wchar and wstring are for UTF-16.

On 1/22/08, torhu <no@spam.invalid> wrote:
> dchar is a 32-bit type, for storing a UTF-32 code unit.  dstring is an array of dchar, in other words a UTF-32 string.  wchar and wstring are for UTF-16.

What dstring is varies from version to version of D, but it's always the correct type to use for strings.

In D1.x, dstring is an alias for dchar[]
In early D2.x, dstring was an alias for const(dchar)[]
In current D2.x, dstring is an alias for invariant(dchar)[]

On 1/22/08, Janice Caron <caron800@googlemail.com> wrote:
> What dstring is varies from version to version of D, but it's always the correct type to use for strings.

Sorry, I meant, for UTF-32 strings.