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?

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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