>________________________________
>From: Robert Jacques <[email protected]>
>To: Discuss the phobos library for D <[email protected]>
>Sent: Thursday, April 21, 2011 4:05 PM
>Subject: Re: [phobos] Time to get ready for the next release
>
>On Thu, 21 Apr 2011 15:57:57 -0400, Jonathan M Davis <[email protected]>
>wrote:
>
>>> How about the amount of existing code it breaks? How about the fact that
>>> it breaks using the same function for both method chaining and with
>>> property syntax?
>>
>> Something like
>>
>> auto b = a.prop1.prop2.prop3;
>>
>> should work. I doesn't at present, but it should. There's a bug report on it.
>
>What about auto b = a.prop1(5).prop2(6).prop3(7); ?
Looks like a poor design. If a setter property returns anything, it should
return the value set. Otherwise:
auto b = a.prop1 = 5; // I would expect b == 5
my solution:
define a setProp1, setProp2, and setProp3 without property semantics. It also
reads better:
auto b = a.setProp1(5).setProp2(6).setProp3(7);
>> As for breaking existing code, _of course_ it's going to. That's to be
>> expected, and I would have thought that that was expected when @property was
>> introduced in the first place.
>
>Actually, no it wasn't expected. @property was introduced with loose
>semantics, not strict semantics. And, by the way, it was judged worth while
>with only loose semantics.
I don't know what messages you read, but strict properties were what was
approved. There have been numerous discussions on the NG regarding properties,
some pro-strict, some pro-loose, but the one which got the deal done was
pro-strict.
The loose semantics were introduced to serve as a translation period, where you
could migrate property code to using @property. From what I remember, Walter
tried to turn on strict properties, but found too many errors in Phobos to deal
with. So it has been back-burnered.
Without strict properties, the author of the code cannot enforce usage
semantics, and therefore, will lead to ambiguities. The only exception I can
see is calling a function with no arguments which returns void without the
parentheses. It cannot be mistaken for a property getter, because it can't be
used as a getter.
-Steve
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