Counter-Proposal: restrict & tagged functions

[Dmitry Olshansky]

On 02-Sep-12 01:13, foobar wrote:
[snip]
 >
 > I skipped the details but I do agree with the general sentiment.
 > This long post begs the question - Why a general annotation
 > mechanism isn't enough to justify adding so much complexity to
 > the language?

It's quite short compared to all of the features it replaces and it had 
to allow for backwards compatibility. And it had to leave place for 
other @annotations as I felt restricting blocks of code is not the only 
use case for annotations.

Also sadly it reiterates a lot of trivia around how tagged functions and 
pointers interact with each another.

About general annotation mechanism. Nobody yet put together a proper 
proposal (if any at all), all I see is people that keep saying: "it's 
simple - just add the general annotation mechanism!".


 > Me thinks that simply tagging malloc/alloca/GC.allocate/etc..
 > with a _user defined_ annotation should be sufficient without the
 > need to introduce all of the above syntax to the language.

Simple tags have no much use on their own - need syntax to use them.
The compiler can deduce their meaning so you also need a way tell the 
compiler: this function can only use "yellow" and "green" functions. 
Then some tags need to be compatible (or convertible with others), then 
there is a need to bundle tags together and so on.

I agree that simply tagging functions with red/green is attractive and 
simple concept but to implement things like say @safe you need more then 
that. You need to tweak what compiler puts in there for you (and 
forbid/allow as it suits your needs).

  In
 > fact, I have a vague memory of reading about green/red marking of
 > code via templates in plain old c++. No extra syntax required.
 >
But xxtra works obviously :)
The method entails carrying around tag arguments apparently. It could be 
labeled as creative but a very backward way to do something simple. More 
specifically it shows that this has to be a language feature so that 
developers can focus on using it instead of being busy implementing it 
by hand.

 > Here's the link:
 > http://www.artima.com/cppsource/codefeaturesP.html


-- 
Olshansky Dmitry