Exception handling macros for C

This repository contains macros to enable OO-like exception handling in C.

It is shamelessly stolen from rampion, with few changes - just a Makefile for the example, and the documentation moved into this README. Mostly because I want this tiny lib in my back pocket.

try-catch.h

RAISE(exception)

When below a TRY block in the call stack, pass the given exception code to the paired CATCH blocks.

When no TRY block is above in the call stack, exits with the given error code.

NOTE: the given exception must be non-zero, otherwise, the behaviour is undefined

RETRY

When below a CATCH block in the call stack, rerun the paired TRY block.

When no CATCH block is above in the call stack, raises a RETRY_EXCEPTION (0x80000001).

TRY(block)

The TRY macro allows you to run the code passed in the given block, passing any RAISE'd exceptions to paired CATCH blocks.

The TRY macro may be paired with zero or more CATCH blocks, but must be paired with a single FINALLY block.

If an exception is RAISE'd, but not handled by any paired CATCH block, then it will be passed to the next TRY/CATCH/FINALLY up the call stack after the paired FINALLY block is called.

TRY(
  // some code
) FINALLY (
  // some code
);

TRY(
  // some code
) CATCH ( exception == 1,
  // what to do with a 1 exception
) CATCH ( exception == 2,
  // what to do with a 2 exception
  // ...
) FINALLY (
  // some code
);

See try-catch-ex.c for a more comprehensive example.

CATCH(condition, block)

The CATCH macro allows a block of code to be run conditionally on a matching exception being RAISE'd within the paired TRY block.

The CATCH macro must be paired with a TRY block and a FINALLY block.

The condition and the block can access the exception variable to find the value of the most recently RAISE'd exception.

The block will be run if:

no prior CATCH block's condition matches the exception
this condition evaluates to a non-zero value

If the CATCH block raises an exception, it will be passed to the next TRY/CATCH/FINALLY block up the scope after the paired FINALLY block is called.

EXCEPT(ex, block)

Shorthand for CATCH(exception == ex, block)

rmalloc.c

void* rmalloc(size_t const nbytes)

Convenience method to allocate nbytes.

returns a pointer to the allocated memory; RAISE's a MALLOC_EXCEPTION (0x80000000) if the memory is not allocated, so it is not necessary to check the return value.

Building the example

make

Fordi / try-catch