Hi Filip,
In Rust there's an operator for error propagation from Result<T, E> types,
it works something like foo()?.bar()?.baz()? etc, either unwrapping or
returning the error value at every step. There is a paper about adding an
operator with this functionality to C++ https://wg21.link/p2561r2. The
other thing that comes to mind are monadic operators in general. I don't
like the try/else/catch syntax here and I think there are probably better
ways of improving the ergonomics here.

Cheers,
Jeremy



On Sun, Feb 16, 2025 at 10:53 AM Filip via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> Hi everyone,
> I want to present to you possible new syntax that would allow for an easy
> improvement of both safety and user experience with any pointer/optional
> type.
>
> We usually need to check many times the validity of an object, which is
> done with an:
> if(wrapperType) // use wrapper
> I frequently use code like:
> return ptrType->get(0)->getParamsPtr()->getName();
>
> With multiple sub wrappers or returned pointers I would love to be simply
> to reuse try keyword in the following way:
>
> try return ptrType->optType.otherWrapper.value;
> else return defaultValue;
>
> In this example try keyword would check if every but last element is
> castable to bool, allows for an access with either . or ->
> Then it would cast element by element in this statement and only go to the
> next element when the cast would succeed and return true.
>
> Possibly single try could also be used with a function like:
> try ptrType->returnedFunc();
>
> The function would be executed only if pointer is not null.
> It could also allow for a bit more complex syntax with catches, however it
> would then expand the meaning to also catch exceptions:
>
> try return ptrType->value;
> else return defaultValue;
> catch (exception e) return exceptionValue;
>
> Equivalent to wrapping entire try else with try catch.
>
> Cheers, Filip
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