On Thu, 13 Oct 2011 17:07:32 -0400, bearophile <[email protected]>
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
