Statically forbid string ~ size_t ?

[Steven Schveighoffer]

On Thu, 13 Oct 2011 17:07:32 -0400, bearophile <bearophileHUGS at lycos.com>  
wrote:

> This comes from a thread in D.learn.
>
> This is a small Python2 program:
>
>
> from sys import argv
> x = len(argv)
> s = "hello"
> s += x
> print s
>
>
> Python is strongly typed so it refuses to append an integer number to a  
> string:
>
> Traceback (most recent call last):
>   File "...\test.py", line 4, in <module>
>     s += x
> TypeError: cannot concatenate 'str' and 'int' objects
>
>
> In Java if you append an integer number to a string the integer number  
> gets first converted to a string:
>
>
> class Main {
>     public static void main(String[] args) {
>         int x = args.length;
>         String s = "hello";
>         s += x;
>         System.out.println(s);
>     }
> }
>
>
> That Java code outputs:
>
> hello0
>
>
> Both Java and Python are far more commonly known than D, and they shape  
> programmers expectations a bit.
>
> This D2 code compiles and runs with DMD 2.056head:
>
>
> void main(string[] args) {
>     int x = args.length;
>     string s = "hello";
>     s ~= x;
> }
>
>
>
> (In this case Python2 is typed more strongly than D.)
>
> I think that int+char is acceptable in D, but string~size_t is not good.  
> I think this is bug prone (especially given the expectations of  
> programmers coming from other languages). So I suggest to statically  
> disallow string~size_t. string~char, string~dchar, and string~string are  
> of course OK.

I think in order to disallow this, you have to disallow dchar = size_t.

IMO, I think it's worth it.  It's very uncommon to create a dchar using an  
integral.

-Steve