MacTech 1 to 12/MacTech-vol-1-12.toast/Source/MacTech® Magazine/Volume 11 - 1995/11.10 Oct 95/C++ Exceptions folder/Samples/exceptions.cp

Text File | 1995-06-10 | 4.9 KB | 198 lines | [TEXT/MPCC]

/*
    EXAMPLE OF EXCEPTION HANDLING USING MW 6.0 - Kent Sandvik
    5/24/95

    Fun with exception handlers for handling unexpected events inside a C++ framework.


    TODO:
        Add set_unexpected when this is supported.

    ISSUES:
        Note this code requires a compiler that handles the basic C++ exception model
            (MW 6.0 or later, Symantec C++ compiler that handles compiler level
            exception handling).

*/

// ______________________________________________________________________________
// INCLUDES
#include <iostream>


// ______________________________________________________________________________
// DEFINES
#define DEBUG true
// #define CATCHEVERYTHING
#define CATCHSPECIFIC


// ______________________________________________________________________________
// MACROS

// This macro will automatically fill in the __FILE__ and __LINE statements
// when a throw is used.

#define THROWEXCEPTION(name, number) \
    throw TMacException( (name), (number), __FILE__, __LINE__)

#define THROWSERIOUSEXCEPTION(name, number) \
    throw TSeriousMacException( (name), (number), __FILE__, __LINE__)


// ______________________________________________________________________________
// EXCEPTION CLASSES

class TMacException
{
public:
    TMacException(const char *theMessage, const OSErr theError) :
                    fMessage(theMessage),
                    fError(theError),
                    fFileName("NO FILE SPECIFIED"),
                    fLineNumber(0L)
                    {};

    TMacException(const char *theMessage, const OSErr theError, const char *theFileName, const long theLineNumber) :
                    fMessage(theMessage),
                    fError(theError),
                    fFileName(theFileName),
                    fLineNumber(theLineNumber)
                    {};

    const char*     GetExceptionMessage(void)     { return fMessage;};
    const OSErr    GetExceptionOSErr(void)        { return fError;};
    const char*    GetExceptionFile(void)        { return fFileName;};
    const long        GetExceptionLine(void)        { return fLineNumber;};

protected:
    const OSErr     fError;
    const char*     fMessage;
    const char*     fFileName;
    const long        fLineNumber;
};


class TSeriousMacException : public TMacException
{
public:
    TSeriousMacException(const char *theMessage, const OSErr theError) :
                    TMacException(theMessage, theError, "NO FILE SPECIFIED", 0L)
                    {};

    TSeriousMacException(const char *theMessage, const OSErr theError, const char *theFileName, const long theLineNumber) :
                    TMacException(theMessage, theError, theFileName, theLineNumber)
                    {};

};

// ______________________________________________________________________________
// TERMINATE DEFAULT FUNCTIONS

void HandleTerminate(void);
void HandleTerminate(void)
{
    cout << "This is the my own terminate function that I've installed!" << endl;
}


// ______________________________________________________________________________
// USER CLASSES

class Foo {
    public:
        Foo();
        void DoASillyThing(void);
};


Foo::Foo()
{
    // cout << "we are inside the Foo constructor" << endl;

}

void Foo::DoASillyThing(void)
{
// Uncomment the test you want to try out:

    // throw TMacException("We did a silly thing", noErr);
    // throw TMacException("We did a silly thing", noErr, __FILE__, __LINE__);
    // throw TSeriousMacException("We did a really serious, silly thing", noErr);
    // throw TSeriousMacException("We did a really serious, silly thing", noErr, __FILE__, __LINE__);

    // THROWEXCEPTION("We did a silly thing", noErr);
     THROWSERIOUSEXCEPTION("We did a really serious, silly thing", noErr);
    // throw "This is an exception that we have not specified!";
}


class Bar {
    public:
        Bar();
};


Bar::Bar()
{
    // cout << "We are inside the Bar constructor" << endl;
    throw TMacException("Inside the Bar constructor", noErr);
}


// ______________________________________________________________________________
// MAIN

void main (void)
{
    Foo* aFoo;
    Bar* aBar;

    // set_terminate(HandleTerminate);

    try
    {
    aFoo = new Foo;

    aFoo->DoASillyThing();

    aBar = new Bar;
    }


// Our catch statements, note that these should be ordered from specific to generic, inheritance wise,
// this because the first valid exception handler is called, and the others will be ignored.

#ifdef CATCHSPECIFIC
    catch (TSeriousMacException &ex)
    {
        long dontWriteToNull;
#ifdef DEBUG
        cerr << "SERIOUS EXCEPTION: " << ex.GetExceptionMessage() << ",  OSErr: " << ex.GetExceptionOSErr() <<
                ", File: " << ex.GetExceptionFile() << ",  Line: " << ex.GetExceptionLine() << endl;
#endif //DEBUG
        // Use real Mac UI to signal about the seriousness to the user of the application.
        Delay(3*60, &dontWriteToNull);
        ExitToShell();

    }

    catch(TMacException &ex)
    {
#ifdef DEBUG
        cerr << "EXCEPTION: " << ex.GetExceptionMessage() << ",  OSErr: " << ex.GetExceptionOSErr() <<
                ", File: " << ex.GetExceptionFile() << ", Line: " << ex.GetExceptionLine() << endl;
#endif //DEBUG
        // Use real Mac UI to signal about the problem to the user of the application.
    }
#endif // CATCHSPECIFIC


#ifdef CATCHEVERYTHING
    catch (...) // catch everything
    {
        cerr <<"We catch every single exception here.\n";
    }
#endif // CATCHEVERYTHING

}