On Sunday, 20 December 2020 at 14:07:56 UTC, Rekel wrote:
The template parameter serves to make Flag!"foo" a distinct
type from Flag!"bar".
Does this mean other flag yes's will not be accepted?
Yes.
https://dlang.org/spec/operatoroverloading.html#dispatch
Also regarding the other examples given, why does Phobos use
templating so heavily, in situation in which I am totally
confused as to why generics would be necessary.
I seem to be totally confused as to how this template system
works. It was introduced as a kind of generic, like in Java,
but things like 'string s' seem to me like parameters.
Java's generics are good for what they do, bolted onto an
existing language in a non-breaking way as they were, but they
are a pale shadow of a real metaprogramming system. D's template
metaprogramming is not anything like Java generics. It's more
akin to C++ templates---much more powerful than what Java offers
you.
If Java's generics are all you know, then breaking through your
confusion and answering your questions is going to require more
than a forum post. You'll want to read up and get some hands on.
I have an introductory post on the D blog which is the first in a
series (that I'll have finally have time to continue in the new
year). It goes over the very, very basics:
https://dlang.org/blog/2020/07/31/the-abcs-of-templates-in-d/
After you read that introduction, you should look into Ali's
coverage of templates in 'Programming in D':
http://ddili.org/ders/d.en/
When you're ready for more, Phillippe Sigaud's tutorial is
excellent (though several old, it's still mostly relevant):
https://github.com/PhilippeSigaud/D-templates-tutorial
