• ixid (11/11) Oct 25 2014 T shadow(T = int)(T a) {
• H. S. Teoh via Digitalmars-d-learn (20/35) Oct 25 2014 The problem gets worse than that. For example:

"ixid" <adamsibson hotmail.com> writes:

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?

"H. S. Teoh via Digitalmars-d-learn" <digitalmars-d-learn puremagic.com> writes:

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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