Exception handling (programming): Difference between revisions

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An uncaught exceptions analyzer exists for the [[OCaml]] programming language.<ref>{{cite web |url=http://caml.inria.fr/pub/old_caml_site/ocamlexc/ocamlexc.htm |title=OcamlExc - An uncaught exceptions analyzer for Objective Caml |publisher=Caml.inria.fr |access-date=2011-12-15 |url-status=live |archive-url=http://archive.wikiwix.com/cache/20110806090555/http://caml.inria.fr/pub/old_caml_site/ocamlexc/ocamlexc.htm |archive-date=2011-08-06 }}</ref> The tool reports the set of raised exceptions as an extended type signature. But, unlike checked exceptions, the tool does not require any syntactic annotations and is external (i.e. it is possible to compile and run a program without having checked the exceptions).

In C++, one can also perform "Pokémon exception handling". Like <syntaxhighlight lang="java" inline>catch (Throwable t)</syntaxhighlight> in Java, C++ supports a <syntaxhighlight lang="cpp">catch (...)</syntaxhighlight> block, which will catch any thrown object. However, <code>catch (...)</syntaxhighlightcode> has the disadvantage of not naming the caught object, which means it cannot be referred to.

<syntaxhighlight lang="cpp">

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// ...

} catch (const std::exception& e) {

// Catching only exceptions:

std::println("An exception was caught: {}", e.what());

}

// Catching all thrown objects:

try {

// ...

} catch (...) {

// Catching all thrown objects:

std::println("An unknown error was caught");

}

</syntaxhighlight>

The [[Rust (programming language)|Rust]] language, instead of using exceptions altogether, instead represents recoverable exceptions as [[result type]]s.<ref>{{cite web |title=std::result - Rust |url=https://doc.rust-lang.org/std/result/index.html |url-status=live |archive-url=https://web.archive.org/web/20231009032955/https://doc.rust-lang.org/std/result/index.html |archive-date=2023-10-09 |access-date=2023-10-09 |website=doc.rust-lang.org}}</ref><ref>{{cite web |date=2011-10-29 |title=stdlib: Add result module · rust-lang/rust@c1092fb |url=https://github.com/rust-lang/rust/commit/c1092fb6d88efe51e42df3aae2a321cc669e12a0 |url-status=live |archive-url=https://web.archive.org/web/20231009033047/https://github.com/rust-lang/rust/commit/c1092fb6d88efe51e42df3aae2a321cc669e12a0 |archive-date=2023-10-09 |access-date=2023-10-09 |website=github.com}}</ref> This is represented as <code>Result<T, E></code> (or <code>expected<T, E></code> in C++). The advantage of result types over checked exceptions is that while both result types and checked exceptions force users to immediately handle errors, they can also be directly represented as a return type within the language's type system, unlike checked exceptions where the declared potentially thrown exception is part of the function signature but not directly part of its return type.

== Dynamic checking of exceptions ==