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digitalmars.D.learn - need to emulate scope(failure) with struct destructor

reply piotrklos <poliklosio happypizza.com> writes:
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.
May 28
parent Dukc <ajieskola gmail.com> writes:
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.
May 28