@trusted AKA most useless statement ever

[Steven Schveighoffer via Digitalmars-d]

On 11/25/16 5:14 AM, Satoshi wrote:
> Simply, it should be replaced by:
>
> void safeFunc() @safe {
>     unsafe {
>         auto vi = doUnsafeCall();
>     }
> }
>
> @trusted functions are prohibited by d-idiom (so I don't know why are
> still in D).

No, they are not. @trusted escapes are for use when you can reasonably 
write most of the code with @safe (and get the benefits of the comipler 
checking safety for you). If you can't reasonably do that, you mark the 
whole function @trusted.

> So, when I need to create a simple window with OpenGL context I need to
> write about 10-15 calls to system functions. But D-idiom[1] for @trusted
> tells me to make @trusted functions as small as possible. OK, it makes
> sense.
>
> but writing 20 times something like:
> auto vi = (() @trusted => glXChooseXFBConfig(...))();
>
> or:
> auto vi = () @trusted { return glXChooseXFBConfig(...); }();
>
> is annoying and just forced me to mark whole class with @trusted...

Marking the whole class as @trusted is fine. "As small as possible" 
might mean you have to mark the whole thing as @trusted, because no code 
can be reasonably marked @safe.

Without seeing your function, I can't say what the best marking should 
be, so maybe it does make sense to add all those trusted escapes. It's 
also possible to simply have an inner function marked @trusted, that 
does the same thing, but is less verbose.

The idea behind @trusted is to mark code as "this needs to be manually 
checked by hand". Any time you have @safe code, but your @trusted 
escapes mean that the @safe code also needs to be checked, you have 
mismarked it.

-Steve