Re: int a = a (Was: Bart's Language)

On 20/03/2025 08:39, David Brown wrote:

On 19/03/2025 22:29, Chris M. Thomasson wrote:

>
The scares me a bit:
_____________________
#include <stdio.h>
>
int main() {
>
     int a = 666;
>
     {
         // Humm... Odd to me...
         int a = a;
>
         printf("%d", a);
     }
>
     return 0;
}

 Yes, that is an unfortunate consequence of the scoping in C - on the line "int a = a;", the new "a" is initialised with its own unspecified value, not with the value of the outer "a".

So the inner 'a' wasn't supposed to mysteriously inherit the outer a's value? (Perhaps due to sharing the same location.) Since the compilers I tried just showed zero not 666.
(Since this thread's subject was an alternative language, in that one it can be done like this, but with the first 'a' outside the function since there are no block scopes; the module is called 'test':
     int a = 666
     proc main =
         int a := test.a
         println a, test.a
The outer 'a' needs that qualifier to access it, in scopes where it would be shadowed. Alternatively an alias can be created then that used instead:
     int a = 666
     int b @ a
I don't know if any of these zero-run-time overhead methods are possible in C. Possibly a union, but that's only if you can define 'a' yourself, and is not an import for example. But then you have to permanently use the union 'qualifier'.)

If the scope of the new variable did not start until after the initialisation, then it would have allowed a number of possibilities that would be a lot more useful than the "disable warnings about uninitialised variables" effect or initialisers which refer to their own address.  For example :
      int a = 123;
     {
         int a = a;
         // local copy that does not affect the outer one
     ...
       int a = 123;
     {
         long long int a = a;
         // Local copy that with expanded size
     ...
      for (int a = 0; a < 100; a++) {
         const int a = a;
         // "Lock" the loop index to catch errors
 As it is, you need to do something like :
      for (int a = 0; a < 100; a++) {
         const int _a = a;
         const int a = _a;
         // "Lock" the loop index to catch errors

You mean locking the loop index so it can't be modified? On the same subject, that other language works like this:
     for a in 0..99 do
         a := 777        # not allowed
Loop variables, if not already defined as variables, are automatically as read-only variables.