User defined safety?

[Adam Ruppe]

My pet feature request could do this too. User defined attributes
combined with a list of functions called by a function.

===

@custom("mysafe") void foo() {}
void bar() {}

@custom("mysafe") void main() {
   foo();
   bar();
}

CheckCustomSafety!("mysafe", main);

template CheckCustomSafety(string attribute, alias func) {
    static if(!__traits(hasCustomAttribute(func, attribute))
           pragma(error, func.stringof ~ " is not " ~ attribute);

      foreach(f; __traits(getCalledFunctions, func))
            CheckCustomSafety!(attribute, f);
}

====

And throw in an or for trusted.



The reason I want this is to check for things more like custom
purity, but I think it'd work for your custom safety too.

(and user defined attributes are just useful for other things too!)


The biggest problem I see with using my idea is the error
message will probably suck.