On Sunday, March 24, 2024 1:41:41 AM MDT Dom DiSc via Digitalmars-d-learn
wrote:
> I'm creating a library that is completely pure, but it doesn't
> compile with pure: at the top because of one impure unittest
> (which uses random to test some things only probabilistic)!
>
> So do I really need to declare every function pure individually
> because of a test?!?
>
> Can we please have a @impure attribute?
> And by the way also @throws and @gc?
> That would make live so much easier...
It's been brought up a number of times before that it would be desirable to
have a way to negate attributes, and maybe we'll get that ability at some
point, but for now, we don't have it. The only attributes that can be
negated are @safe, @trusted, and @system, because using one of them directly
on a function overrides any others that are applied more globally. So, for
now, you cannot apply pure to an entire module and then have it not apply to
something within the module (though you could put that one test at the top
before you apply pure).
Another thing you could do would be to use debug {} to ignore attributes
within that block (though then that code will only be run when building with
-debug). How much sense that makes depends on what your test is doing, but
it is a way to get around pure in code that isn't intended to be used in
production.
All of that being said, I'd be inclined to argue that in general,
mass-applying attributes is asking for trouble. It works to a point, but it
makes it easy to forget which attributes apply, and in some cases,
attributes get ignored when they're mass-applied (though that's mostly on
types IIRC). It makes more sense when you're applying an attribute to the
entire module and not just a section of a module, but it does have a
tendency to become a maintenance problem - particularly when it's code that
more than one person works on. It also makes code harder to review, because
diffs won't include any of the attributes that are being mass-applied,
making it easy to miss the fact that a particular attribute applies to the
code being changed.
So, yes, you've run into a problem that it would be nice to have a better
fix for, but even if we could negate attributes in general, there are good
reasons to prefer to avoid mass-applying attributes.
- Jonathan M Davis
