On Sunday, 23 September 2012 at 21:52:23 UTC, Timon Gehr wrote:
On 09/23/2012 10:57 PM, Ali Çehreli wrote:
...
Also, I think your code should have passed a range like R.init
to
takeExactly, not R, which is a type:
takeExactly(R.init, 1)
I don't know why your code compiles.
See discussion here:
http://d.puremagic.com/issues/show_bug.cgi?id=8220
Interesting. Thanks.
On Sunday, 23 September 2012 at 21:53:20 UTC, Jonathan M Davis
wrote:
On Sunday, September 23, 2012 14:47:27 Timon Gehr wrote:
template Hello(R) if(is(typeof(R._input.takeExactly(2)) == R)){
alias R Hello;
}
Thanks. That does the trick quite cleanly, though you'd think
that it would be
possible to test whether a template argument is the result of
takeExactly
without caring or knowing about the guts of takeExactly. So,
this isn't a
general purpose solution at all, when I think that there should
be one. Still,
I don't need a general purpose one for what I'm doing, so this
should work
just fine.
- Jonathan M Davis
What is wrong with my proposed solution?
----
import std.range;
template Hello(R)
if ( is(typeof(takeExactly(R.init, 1))) &&
is(R == typeof(takeExactly(R.init, 1)))
)
{
alias R Hello;
}
struct R
{
enum empty = false;
@property int front();
void popFront();
}
struct S{}
void main( ) {
Hello!(int[]) a; //OK
Hello!R b; //Fails second Check: R == typeof(...)
Hello!S c; //Fails first check:
is(typeof(takeExactly(...)))
}
----
Forgive me again if there is something wrong with it, but this
time, I think it is correct...?
