"Exceptions will fade away in modern languages"

Dukc ajieskola at gmail.com
Thu Nov 26 04:41:57 UTC 2020

On Saturday, 21 November 2020 at 23:05:19 UTC, IGotD- wrote:
> I reacted to the comment of Walter Bright about exceptions in 
> the "Destroy All Memory Corruption" presentation. The point he 
> made that exceptions don't play well with compile time data 
> flow analysis. He also mentioned that he thinks that exception 
> will become obsolete in the future. Exceptions are used in many 
> languages today and even the newest ones so I can't see a trend 
> here.
> That raises the question what method is going to replace 
> exceptions in that case?
> Will D introduce an alternative method of error handler that 
> plays better with @live?

A (library-based) sum type used as error value, probably. That's 
what Rust does, except it also has language support for the 
concept. Because I personally don't like exceptions much, I have 
some experience from that approach (using TaggedAlgebraic). It 
feels somewhat cumbersome - Rust probably is better fit for that 
than we are. But D still can do more tricks C++, Java or C# can, 
probably. `with` and `final switch` statements are useful in my 
experience. As is the possibility to 
`sumTypeVariable.visit!(...)`, but it has the downside that you 
always exit that statement the same way -you can't `break` or 
`goto` out.

Why I don't like exceptions? I feel I am making my functions less 
general when using them. For example, when parsing XML and 
encountering a syntax error, if I throw on the error I 
essentially declare that my function is only intended for 
generally sound XML -it isn't intended to count or list syntax 
errors in a text full of them. Errors in return codes are use 
case agnostic in this regard. Perhaps this is one of the reasons 
why Walter considers exceptions an aged concept.

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