On Fri, 09 Mar 2012 19:32:06 -0500, David Nadlinger <s...@klickverbot.at>
wrote:
On Friday, 9 March 2012 at 23:39:25 UTC, Steven Schveighoffer wrote:
I want to stress again the difference between C++'s namespaces, and D's
module import mechanism. In C++, you *deliberately* pull a namespace
into your scope (and usually only in the implementation file, which
doesn't affect any other implementation files), whereas in D, a
standard "import std.datetime" *automatically* pulls its namespace into
your scope, and any public imports it has made.
To be honest, I don't quite see the big difference here. Just as you can
only #include a »namespaced« file without using a using directive, you
can »static import« a module in D. You seem to be arguing that we
shouldn't encourage use of these features (cf. the std.log discussion),
but I can't quite follow you there.
The big difference is, the most straightforward and most exemplified
import syntax is:
import modulename;
So to argue this is not the default syntax, or not the most desirable/used
syntax is just plain invalid.
In contrast, C++'s import syntax is:
#include "modulename.h"
which does not import any namespaces into your scope.
Why would _not_ using static and selective imports be desirable? Don't
we generally discourage people from write »using namespace std« in C++
or »import *« in Python as well? (I'm aware that the D module system is
different, but the general idea is the same)
I don't think we should make the default the most conflicting or difficult
to use method. For example, to say:
"always import log using:
import log = std.log"
Is not as good as just not having to say that (i.e. import std.log like
you would any other module). I remember Tango had a couple of modules
like that, and I thought it was pretty confusing.
That doesn't mean you can't utilize those facilities (and I *don't*
discourage them). I just don't think it should be a barrier to usage.
-Steve
