Logging and Error Handling

The C++ subengine defines the following logging levels:

INFO
DEBUG
WARNING
ERROR
FATAL

The engine is in the debug mode when the debug tracing is enabled for the main engine. The debug messages are printed only when the engine is in the debug mode.

To log a single string, use the v2_log_<level>_string set of function that are declared in v2/subengine.h.

For convenience, the variadic functions (such as, printf-like) are declared and implemented in the optional v2/log.h header. If you want to include their implementation in your operator library, then before including v2/log.h in a source file, define the V2_LOG_IMPLEMENTATION macro.

For example:

#define V2_LOG_IMPLEMENTATION
#include <v2/log.h>
#undef V2_LOG_IMPLEMENTATION

This helps to include the header from multiple files at wherever those function declarations are required, and still continue to keep their implementation in a single place.

Error Handling

All types of handlers, which users can provide to the subengine have the return type, const char*. This return type is a null-terminated string containing the error message or a NULL value, if no error occurred. Errors returned by handlers are always fatal (otherwise, use v2_log_error_string or v2_log_error instead).