Statically forbid string ~ size_t ?

[Steven Schveighoffer]

On Thu, 13 Oct 2011 18:34:35 -0400, Don <nospam at nospam.com> wrote:

> On 13.10.2011 23:07, bearophile 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.
>>
>> So far I have written no enhancement request/bug report on this because  
>> I am not so sure...
>
> The problem is things like:
> int i;
> string s = "0x" ~ ('0' + x);
> since char + int --> int.
>

string s = "0x" ~ cast(char)('0' + x);

Problem solved.

-Steve