D's Auto Decoding and You

[Steven Schveighoffer via Digitalmars-d-announce]

On 5/17/16 1:49 PM, Rory McGuire via Digitalmars-d-announce wrote:
>
> On 17 May 2016 16:21, "Steven Schveighoffer via Digitalmars-d-announce"
> <digitalmars-d-announce at puremagic.com
> <mailto:digitalmars-d-announce at puremagic.com>> wrote:
>  >
>  > On 5/17/16 10:06 AM, Jack Stouffer wrote:
>  >>
>  >> http://jackstouffer.com/blog/d_auto_decoding_and_you.html
>  >>
>  >> Based on the recent thread in General, I wrote this blog post that's
>  >> designed to be part beginner tutorial, part objective record of the
>  >> debate over it, and finally my opinions on the matter.
>  >>
>  >> When I first learned about auto-decoding, I was kinda miffed that there
>  >> wasn't anything in the docs or on the website that went into more
>  >> detail. So I wrote this in order to introduce people who are getting
>  >> into D to the concept, it's benefits, and downsides. When people are
>  >> confused in Learn why typeof(s.front) == dchar then this can just be
>  >> linked to them.
>  >>
>  >> If you think there should be any more information included in the
>  >> article, please let me know so I can add it.
>  >
>  >
>  > Starting to read it, see errors in your examples:
>  >
>  > is(s[0] == immutable char) -> is(typeof(s[0]) == immutable(char))
>  > is(s.front == dchar) -> is(typeof(s.front()) == dchar)
>  >
>  > I'm not sure if you need the parens after front, but if it's not
> marked as @property, then this returns a function.
>  >
>
> If I remember correctly adding the brackets then goes against best
> practices because you can't be sure the underlying implementation of a
> range is using a function for .front.
>

Right, but there's this:

struct MyRange
{
    private int _val;
    int front() { return _val; }
    bool empty() { return _val < 100; }
    void popFront() { ++_val; }
}

static assert(isInputRange!MyRange);
static assert(!is(typeof(MyRange.init.front) == int));

This is why I recommended the parentheses. In reality, you should do 
ElementType!MyRange, which does the correct thing. But is(typeof(...)) 
doesn't always work like you might expect.

-Steve