• Martin Drasar (32/34) Sep 29 2013 Hi,
• Andrej Mitrovic (3/4) Sep 29 2013 You should call it like this:
• Andrej Mitrovic (8/13) Sep 29 2013 Btw, as for the reason why that used to work, I think it's one of
• Martin Drasar (8/23) Sep 29 2013 Hi Andrej,
• Timon Gehr (2/13) Sep 29 2013 Mark 'save' with @property and it will work.
• Martin Drasar (5/6) Sep 29 2013 Well, d'oh! It really works now, thanks Timon. And the documentation
• monarch_dodra (5/13) Sep 29 2013 Too late to change it now, but agreed.
• Martin Drasar (6/11) Sep 30 2013 I don't doubt there is a good reason, however it should be probably

Martin Drasar <drasar ics.muni.cz> writes:

Hi,

I have upgraded to dmd 2.063.2 and have some troubles making my custom
bidirectional range work (it used to). In fact, even this code fails on
assert and I am not really sure why...

import std.range;

struct MyRange(T)
{
  private:
  T[] data;

  public:
  T front()  property { return data[0]; }
  T back()   property { return data[0]; }
  void popFront() {}
  void popBack()  {}
  bool empty()  property { return false; }
  auto save()
  {
    typeof(this) result;
    result.data = data;
    return result;
  }
}

static this()
{
  MyRange!string tmp;
  static assert(isInputRange!(MyRange!string));
  static assert(is(typeof(tmp.save) == MyRange!string));
}

I get this when trying to compile:

 drasar uriel:/tmp$ dmd test.d
 test.d(26): Error: static assert  (is(pure nothrow  safe MyRange!(string)() ==
MyRange!(string))) is false

Do you have an idea?

Thanks,
Martin

"Andrej Mitrovic" <andrej.mitrovich gmail.com> writes:

On Sunday, 29 September 2013 at 20:37:13 UTC, Martin Drasar wrote:
   static assert(is(typeof(tmp.save) == MyRange!string));

You should call it like this:

static assert(is(typeof(tmp.save()) == MyRange!string));

"Andrej Mitrovic" <andrej.mitrovich gmail.com> writes:

On Sunday, 29 September 2013 at 20:42:20 UTC, Andrej Mitrovic 
wrote:
 On Sunday, 29 September 2013 at 20:37:13 UTC, Martin Drasar 
 wrote:
  static assert(is(typeof(tmp.save) == MyRange!string));

 You should call it like this:

 static assert(is(typeof(tmp.save()) == MyRange!string));

Btw, as for the reason why that used to work, I think it's one of 
these:

In earlier versions typeof() might have checked the return type 
of the function, rather than the type of the function itself.

And purity (and other attributes) are now inferred for functions 
in templated aggregates. (but it may not be related to your code).

Martin Drasar <drasar ics.muni.cz> writes:

On 29.9.2013 22:45, Andrej Mitrovic wrote:
 On Sunday, 29 September 2013 at 20:42:20 UTC, Andrej Mitrovic wrote:
 On Sunday, 29 September 2013 at 20:37:13 UTC, Martin Drasar wrote:
  static assert(is(typeof(tmp.save) == MyRange!string));

 You should call it like this:

 static assert(is(typeof(tmp.save()) == MyRange!string));

 
 Btw, as for the reason why that used to work, I think it's one of these:
 
 In earlier versions typeof() might have checked the return type of the
 function, rather than the type of the function itself.
 
 And purity (and other attributes) are now inferred for functions in
 templated aggregates. (but it may not be related to your code).

Hi Andrej,

this is just a copy&paste of code from std.range documentation. In fact,
the plain isForwardRange fails. It was just expanded to show where it fails.

Btw, I have this in range.d isForwardRange check:
static assert (is(typeof(r1.save) == R));

Does that mean that the std.range code is wrong?

Martin

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/29/2013 10:25 PM, Martin Drasar wrote:
 Hi,

 I have upgraded to dmd 2.063.2 and have some troubles making my custom
 bidirectional range work (it used to). In fact, even this code fails on
 assert and I am not really sure why...
...
 I get this when trying to compile:

 drasar uriel:/tmp$ dmd test.d
 test.d(26): Error: static assert  (is(pure nothrow  safe MyRange!(string)() ==
MyRange!(string))) is false

 Do you have an idea?

 Thanks,
 Martin

Mark 'save' with  property and it will work.

Martin Drasar <drasar ics.muni.cz> writes:

On 29.9.2013 23:19, Timon Gehr wrote:
 Mark 'save' with  property and it will work.

Well, d'oh! It really works now, thanks Timon. And the documentation
does not call it as a function anywhere. But... having save a property
seems counterintuitive, at least on semantic level.

Martin

"monarch_dodra" <monarchdodra gmail.com> writes:

On Monday, 30 September 2013 at 06:24:22 UTC, Martin Drasar wrote:
 On 29.9.2013 23:19, Timon Gehr wrote:
 Mark 'save' with  property and it will work.

 Well, d'oh! It really works now, thanks Timon. And the 
 documentation
 does not call it as a function anywhere. But... having save a 
 property
 seems counterintuitive, at least on semantic level.

 Martin

Too late to change it now, but agreed.

The new property rules mean you can easily make it a non-property 
and break nothing, but calling save with parrens in generic code 
will not be possible.

Martin Drasar <drasar ics.muni.cz> writes:

On 30.9.2013 8:28, monarch_dodra wrote:
 Too late to change it now, but agreed.
 
 The new property rules mean you can easily make it a non-property and
 break nothing, but calling save with parrens in generic code will not be
 possible.

I don't doubt there is a good reason, however it should be probably
better reflected in the documentation. There the 'popBack', 'save', etc.
are reffered to only as primitives and the rest is left as an excersise
for the reader.

Martin