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cpl_error.h File Reference

CPL error handling services. More...

Functions
		void CPL_DLL	CPLError (CPLErr eErrClass, int err_no, const char *fmt, ...)
			Report an error. More...
		void CPL_DLL	CPLErrorReset ()
			Erase any traces of previous errors. More...
		int CPL_DLL	CPLGetLastErrorNo ()
			Fetch the last error number. More...
		const char CPL_DLL*	CPLGetLastErrorMsg ()
			Get the last error message. More...
		CPLErrorHandler CPL_DLL	CPLSetErrorHandler (CPLErrorHandler)
			Install custom error handler. More...
		void CPL_DLL	CPLDebug ( const char *, const char *, ... )
			Display a debugging message. More...
		void CPL_DLL	_CPLAssert ( const char *, const char *, int )
			Report failure of a logical assertion. More...

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Detailed Description

CPL error handling services.

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Function Documentation (1)

void CPLError (CPLErr eErrClass, int err_no, const char * fmt, ...)

Report an error.

This function reports an error in a manner that can be hooked and reported appropriate by different applications.

The effect of this function can be altered by applications by installing a custom error handling using CPLSetErrorHandler().

The eErrClass argument can have the value CE_Warning indicating that the message is an informational warning, CE_Failure indicating that the action failed, but that normal recover mechanisms will be used or CE_Fatal meaning that a fatal error has occured, and that CPLError() should not return.

The default behaviour of CPLError() is to report errors to stderr, and to abort() after reporting a CE_Fatal error. It is expected that some applications will want to supress error reporting, and will want to install a C++ exception, or longjmp() approach to no local fatal error recovery.

Regardless of how application error handlers or the default error handler choose to handle an error, the error number, and message will be stored for recovery with CPLGetLastErrorNo() and CPLGetLastErrorMsg().

Parameters:

eErrClass - one of CE_Warning, CE_Failure or CE_Fatal.

err_no - the error number (CPLE_*) from cpl_error.h.

fmt - a printf() style format string. Any additional arguments will be treated as arguments to fill in this format in a manner similar to printf().

void CPLErrorReset ()

Erase any traces of previous errors.

This is normally used to ensure that an error which has been recovered from does not appear to be still in play with high level functions.

int CPLGetLastErrorNo ()

Fetch the last error number.

This is the error number, not the error class.

Returns:

the error number of the last error to occur, or CPLE_None (0) if there are no posted errors.

const char * CPLGetLastErrorMsg ()

Get the last error message.

Fetches the last error message posted with CPLError(), that hasn't been cleared by CPLErrorReset(). The returned pointer is to an internal string that should not be altered or freed.

Returns:

the last error message, or NULL if there is no posted error message.

CPLErrorHandler CPLSetErrorHandler (CPLErrorHandler pfnErrorHandler)

Install custom error handler.

Allow the library's user to specify his own error handler function. A valid error handler is a C function with the following prototype:

     void MyErrorHandler(CPLErr eErrClass, int errno, const char *msg)
 

Pass NULL to come back to the default behavior. The default behaviour is to write the message to stderr.

The msg will be a partially formatted error message not containing the "ERROR d:" portion emitted by the default handler. Message formatting is handled by CPLError() before calling the handler. If the error handler function is passed a CE_Fatal class error and returns, then CPLError() will call abort(). Applications wanting to interrupt this fatal behaviour will have to use longjmp(), or a C++ exception to indirectly exit the function.

Parameters:

pfnErrorHandler - new error handler function.

Returns:

returns the previously installed error handler.

void CPLDebug (const char * pszCategory, const char * pszFormat, ...)

Display a debugging message.

The category argument is used in conjunction with the CPL_DEBUG environment variable to establish if the message should be displayed. If the CPL_DEBUG environment variable is not set, no debug messages are emitted (use CPLError(CE_Warning,...) to ensure messages are displayed). If CPL_DEBUG is set, but is an empty string or the word "ON" then all debug messages are shown. Otherwise only messages whose category appears somewhere within the CPL_DEBUG value are displayed (as determinted by strstr()).

Categories are usually an identifier for the subsystem producing the error. For instance "GDAL" might be used for the GDAL core, and "TIFF" for messages from the TIFF translator.

Parameters:

pszCategory - name of the debugging message category.

pszFormat - printf() style format string for message to display. Remaining arguments are assumed to be for format.

void _CPLAssert (const char * pszExpression, const char * pszFile, int iLine)

Report failure of a logical assertion.

Applications would normally use the CPLAssert() macro which expands into code calling _CPLAssert() only if the condition fails. _CPLAssert() will generate a CE_Fatal error call to CPLError(), indicating the file name, and line number of the failed assertion, as well as containing the assertion itself.

There is no reason for application code to call _CPLAssert() directly.

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