On Sat, Oct 25, 2014 at 12:28:39PM +0000, ixid via Digitalmars-d-learn wrote:
> T shadow(T = int)(T a) {
> alias T = string;
> T b = "hi";
> T c = 1; // Error
>
> writeln(typeof(a).stringof); // int
> writeln(typeof(b).stringof); // string
>
> return a;
> }
>
>
> Are there uses for this shadowing of type names? It seems a little
> dangerous, for example ulong T could be shadowed by uint T. Is there a
> reason to allow it?
The problem gets worse than that. For example:
----external_library.d----
module external_library;
alias T = string;
----main.d----
module main;
void func(T = int)(T i) {
import external_library;
pragma(msg, T.stringof); // prints 'string'
}
void main() {
func(1);
}
Imagine that the 'alias T' was not present in an earlier version of the
library, but now has been added by the library author. Suddenly, user
code breaks without warning.
T
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Error: Keyboard not attached. Press F1 to continue. -- Yoon Ha Lee, CONLANG
