Exception.h File Reference

#include <string>
#include <buffy/stringf.h>

Go to the source code of this file.

Classes
class	InstallUnexpected
	Install an unexpected handler for the duration of its scope. More...
class	Exception
	This is the base class for all exceptions used in the system. More...
class	ContextException
	Exception with a description of the throwing context. More...
class	InterruptedException
	It is a direct child of ContextException, and has the very same semantics. More...
class	WaitInterruptedException
	It is a direct child of InterruptedException, and has the very same semantics. More...
class	ConsistencyCheckException
	It is a direct child of ContextException, and has the very same semantics. More...
class	OutOfRangeException
class	ValOutOfRangeException< C >
	This exception is to be thrown when an index checking fails, providing informations on the acceptable index range and on the offending value. More...
class	SystemException
	This is the base class for exceptions that depend on system events, like exceptions on file or network I/O, on database access and so on. More...
class	FileException
	It is a direct child of SystemException, and has the very same semantics. More...
Functions
void	DefaultUnexpected ()
	This is an unexpected handler provided by the library.

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Detailed Description

This file provides the root of the exception hierarchy. The goal of this hierarchy is to provide the most possible information on what caused the exception at the least possible cost for the programmer.

Every exception is the descendent of Exception that, in turn, extends the std::exception class of the STL.

Further descendents of Exception add functionality and automatisms to error message generation:

• ContextException extends Exception to provide informations on the context in which the exception was raised
• ConsistencyCheckException extends ContextException to be a base class for all exception raised on failure of a consistency check; IndexOutOfRangeException is one example of such exceptions, to be used when checking that a value (such as an index) fails betweed two given bounds.
• SystemException extends ContextException to carry informations about error conditions reported by external services, like the Operating System, a database interface or an interface used to communicate to some network server. In particular, it provides the logic needed to make use of the error descriptions provided by the external services, as strerror(3) does for the operating system's error conditions. FileException is an example of such exceptions, to be used to report error conditions happened during File I/O.

Example exception raising:

        void MyFile::open(const char* fname) throw (FileException)
        {
            if ((fd = open(fname, O_RDONLY)) == -1)
                throw FileException(errno, stringf::fmt("opening %s read-only", fname));
        }

Example exception catching:

      try {
            myfile.open("/tmp/foo");
        } catch (FileException& e) {
            fprintf(stderr, "%.*s: aborting.\n", PFSTR(e.toString()));
            exit(1);
        }

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Function Documentation

void DefaultUnexpected (   )

This is an unexpected handler provided by the library. It prints to stderr a stack trace and all possible available informations about the escaped exception. To have the function names in the stack trace, the executables need to be linked using the -rdynamic flag.

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