pure, safe and generalized attributes

[Koroskin Denis]

Good, but I'd rather see 'thread-safe' built-in attribute.

On Fri, 04 Apr 2008 11:19:49 +0400, Knud Soerensen  
<4tuu4k002 at sneakemail.com> wrote:

>
> With all the talk about pure, safed and transitivity.
> I think the time is right for a discussion about
> user defined code attributes.
>
> Code attributes is just meta data for the code.
> Normally, this meta data is stored in revision systems, databases, in
> the code comments or just plain left out.
> But there is some advantages by placing them in the code and letting the
> compiler take care of them.
>
> Scott Meyers does a good job of introducing the subject in
> http://video.google.com/videoplay?docid=-4728145737208991310
>
> ----
>
> The simplest use of code attribute I can imagine
> is a attribute which indicate that this piece of code have been review.
> It could be defined by.
> attribute KilroyWasHere;
>
> and used like
> int func(param p1) KilroyWasHere
> {
> ...
> }
>
> You can do this with comments as well, but imagine you use.
>
> attribute FixMe warn;
>
> and the compile gave you a warning every time it sees the FixMe  
> attribute.
>
> attribute FixMe fail;
>
> Would give you a error and the build would fail.
>
> ----
>
> The next attribute indicate that the code is license under the GPL.
>
> attribute GPL transitive;
>
> Here the transitive keyword tells the compiler that the attribute is
> transitive, and the compiler should check that every function called
> also has the attribute GPL.
> ----
>
> attribute LGPL deny GPL;
>
> This attribute is not transitive but the code should not call GPL code.
> -----
>
> attribute safe transitive allow pure;
>
> Define an attribute for thread-safety which is transitive but also
> allows pure functions. pure would be a build in attribute because it
> need to be able to validate the code.
> -----
>
> Now imagine a big team need to refactor a big ugly code base.
>
> Then the following attributes will allow the team to mark
> the code after how it smells (good, okay or bad);
>
> attribute good transitive warn;
> attribute okay transitive warn allow good;
> attribute bad transitive warn allow okay,good;
>
> The attributes only issue warnings, so they wouldn't stop the code form
> compiling, and only when more smelly code is called.
>
>
> I hope that I have illustraded that user definded code attributes
> could be very useful.
>
> Knud