need to emulate scope(failure) with struct destructor

[Dukc via Digitalmars-d-learn]

On Sunday, 28 May 2017 at 20:06:42 UTC, piotrklos wrote:
> I need to perform an action, in multiple separate functions, if 
> scope exits with an exception. The trouble is I don't want to 
> litter my code with scope(failure) everywhere. I already create 
> an instance of a struct at each location, with the sole purpose 
> of doing things at the end of scope.
> So my code looks like:
>
> function1()
> {
> RAIIType transactionHandler;
> scope(failure) action;
> //code
> }
>
> function2()
> {
> RAIIType transactionHandler;
> scope(failure) action;
> //code
> }
>
> function3()
> {
> RAIIType transactionHandler;
> scope(failure) action;
> //code
> }
>
> etc.
>
>  Ideally I would put the statement from scope(failure) in the 
> struct's destructor and delete the scope(failure) statements.
> I would need something like c++'s std::uncaught_exceptions() to 
> check if an exception is in flight.
>
> Is there something like this in D?
>
> PS I think that we have here a more general problem, because 
> dlang is missing a feature for composition of scope(...) 
> statements.

Hard to do that way, only mixins come to mind.

However, if you want to do the same thing anywhere the failure 
happens, most likely you want to do that at where you catch the 
exception.

Another less likely, but possible, way is to have the struct 
destructor to do the scope(exit) part only if it gets destroyed 
in some certain state. For example, if the transaction receiver 
is null.