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Re: [std-proposals] RTTI in current_exception

From: Thiago Macieira <thiago_at_[hidden]>
Date: Mon, 09 Jan 2023 16:14:19 -0800
On Monday, 9 January 2023 08:39:20 PST Jason McKesson via Std-Proposals wrote:
> Is this for printing out some debugging information? Are you going to
> start comparing it to other `type_info`s and doing a bunch of casting
> to figure out what it could be (which would be exceedingly pointless)?
> What is the point of getting this information if there's nothing you
> can really do about it?

I should point out that "comparing type_info to know class typeids" is exactly
what catch will do for you and more efficiently. The only reason you'd write
manual code is if the list of types to be matched against isn't known at
compile-time but instead is itself runtime-populated.

> As for your suggestion that we shouldn't be able to throw anything
> that isn't derived from `std::exception`, again I ask: why? What would
> that do which you can't do otherwise? The only functionality of
> `std::exception` is that it carries a message via a `char const*`. But
> even that could just be an empty string, so you are guaranteed
> precisely *nothing*.

We can't remove that ability because code exists that uses that.

It's bad practice though. And since it should be avoided, the proposal needs
to explain why you're in fact adding functionality for its benefit. If the
thrown type derives from std::exception, you can catch by std::exception and
run typeid on the type you got.

Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel DCAI Cloud Engineering

Received on 2023-01-10 00:14:31