Try-catch statements

NOTE: Try-catches are not yet supported. They are a planned feature, but will take a long time until they are implemented

A try-catch statement will try running the code in the try block, and if any exceptions are thrown, they are going to be handled by the catch statement (if the types of the exceptions match, of course).

Catches

A catch is a part of the try-catch statement, that consists of a single "parameter" of sorts, that is the type of exception that this catch is going to handle. This can be a contract as well, but due to some inefficiencies in that regard, it's recommended to handle separate classes.

Nameless catches

If a catch doesn't specify the name of the exception it's getting, then the catch will only listen for the exception thrown. Such catches can specify multiple types they're listening for.

Typeless catch

Such catch doesn't have any parenthesis and it listens for all exceptions.

Syntax

catch (Type name) statement;

// Or
catch (Type1, Type2, Type3, Type3, ... TypeN) statement;

// Or
catch statement;

Order of catch executions

Since a try-catch can have multiple catches, they will be executed in order. If one of them breaks out of the try-catch statement, via break, goto, another throw or return, the chain of catches is going to be broken and the try-catch statement is going to be left.

Throw

The throw statement accepts an expression of any type, or no expression. The throw statement acts like the return statement, but instead of a meaningful return value, it communicates to the caller that something has went wrong, and sends the provided value to the caller. The thrown value propagates the call stack, until a caller that has provided an appropriate catch is reached.

Possible optimizations

Two catches that have the same types will be combined, for example:

void main() {
    try func();
    catch (int err) ...;
    catch (int) ...;
}

Will result in code which looks like this:

void main() {
    try func();
    catch (int err) {
        catch1 ...;
        catch2 ...;
    }
}

If a catch catches a type that the function doesn't throw, the catch will be omitted.

++C architecture for catching exceptions

In the ++C ecosystem, throw-catch works by passing catch callbacks to the function calls inside the try statement.

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