On 02/10/2013 03:42 PM, kenji hara wrote:
2013/2/10 kenji hara <k.hara...@gmail.com <mailto:k.hara...@gmail.com>>I opened the pull request #1413 in the beta term for 2.061, but it had _accidentally_ released without deeply discussion. https://github.com/D-Programming-Language/dmd/pull/1413 I think and believe that we MUST reset things. Why I argue that the syntax `alias this = sym;` is wrong?
Do you have any arguments that do not also apply to alias sym this; ?
Because: 1. A normal alias declaration (creating aliased name for existing symbol) and alias this feature (making a *subtyped* struct through implicit access to its field)
Actually that is not what subtyping means.
are entirely different and has distinct semantics.
Yet they already deliberately share the same piece of syntax. The problems cannot be attributed to the alias assignment syntax addition.
They merely share a keyword 'alias'.
No, they share the entire declaration syntax. alias foo this; alias foo that;
2. Instead, we can have much more consistent,
alias foo that; // ok alias foo this; // ok alias that=foo; // ok alias this=foo; // uh...
useful,
All are of the same usefulness.
and scalable syntax. At the same time, I proposed a new syntax `alias this : ident;` for alias this feature.
Yes, what is the point? Why would a new syntax that's deliberately inconsistent with alias syntax require an 'alias' keyword? It is not an alias. The other special aggregate members are just specially named symbols.
https://github.com/D-Programming-Language/d-programming-language.org/pull/200 struct S { int value; alias this : value; // proposed syntax } Benefits of the proposed syntax are: 2a. It is consistent with class inheritance syntax `class C : B {}`.
It's hardly consistent, and you were opposed to entirely different constructs having similar syntax above!
2b. It is scalable for multiple alias this feature, as like `alias this : sym1, sym2, ...;` .
TDPL says: alias sym1 this; alias sym2 this; ...
If D community highly require the syntax `alias this = sym`, I'll agree to adding it again. But for that, we should discuss about its cost and benefit. ...
The syntax to access the alias this functionality is quite whacky. Applying a partial fix without going all the way just increases confusion.
