portability

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Portability

This library should compile in any good old C compiler. It uses nothing but standard C functions. In order to use exceptions4c you have to drop the two files (e4c.h and e4c.c) in your project and remember to #include the header file from your code.

Keywords

All of the names of the functions, defined types and macros start with the preffix e4c_ in order to prevent namespace pollution. However, exceptions4c defines the next set of keywords (through macros) for convenience:

• try
• finally
• throw
• catch
• with
• use
• using

If, for some reason, you don't want the library to define these keywords, you can compile the library with the E4C_NOKEYWORDS compile-time parameter and use their respective alternate versions:

• E4C_TRY
• E4C_FINALLY
• E4C_THROW
• E4C_CATCH
• E4C_WITH
• E4C_USE
• E4C_USING

C99-only Features

There is a convenience macro that lets you to compose a formatted message and throw an exception on the fly.

int bytes = 1024;
void * buffer = malloc(bytes);
if(buffer == NULL){
    throwf(NotEnoughMemoryException, "Could not allocate %d bytes", bytes);
}

This macro relies on two features that were introduced in C99:

• Variadic macros
• Buffer-safe function vsnprintf

In order not to create compatibility issues, this macro will only be defined when the __STDC_VERSION__ compile-time parameter is defined with a value greater than or equal to 199901L, or HAVE_C99_VARIADIC_MACROS is defined.

Of course, the alternative way to compose a message and then throw it would be to call snprintf (or its unsafe alternative sprintf):

int bytes = 1024;
void * buffer = malloc(bytes);
if(buffer == NULL){
    char message[E4C_EXCEPTION_MESSAGE_SIZE];
    snprintf(message, E4C_EXCEPTION_MESSAGE_SIZE, "Could not allocate %d bytes", bytes);
    throw(NotEnoughMemoryException, message);
}

The semantics of this macro are the same as for the throw macro.

At least one argument must be passed right after the format string. The message will be composed through the function vsnprintf with the specified format and variadic arguments. For further information on the formatting rules, you may look up the specifications for the function vsnprintf.

Multi-threading

In case your application uses threads, exceptions4c relies on pthreads, the POSIX application programming interface for writing multithreaded applications. This API is available for most operating systems and platforms. You only need to compile the library with the E4C_THREADSAFE compile-time parameter.