CODEWITHSUNDEEP
c++exception
jviotti
jviotti

Reputation: 18909

C++ good error handling approach

I'm starting to write some code using C++ and I have this simple class method from a simple task manager program I'm writing as an experiment:

void Task::setText(string text)
{
    if(text.length() > MIN_LENGTH)
    {
        this->text = text;
    }
}

As you can see, this method sets the class text attribute to the one passed to the method if it's length is higher than the MIN_LENGHT variable that is defined above the code I've shown. So I have to do something if the condition does not evaluate to true for the string passed to the method.

In the C++ book I bought, error handlings are not explained, instead it just uses assert everywhere. As assert just aborts the program if the expression is false, and this is intended as input validation, I looked for a better approach.

This search led me to C++ exceptions. There it explains how to create exceptions by creating a class that inherits from exception.

Good OOP practice says that every class should be independent from the others in the program. So where should I put this exception class I create? In the same header I define my Task class in? Or should it be in task.cpp where I define every method of the class?

Maybe this is a silly question but just want to be secure and follow a good software architecture practices from the beginning.

Upvotes: 3

Views: 1323

Answers (3)

Kirill Kobelev
Kirill Kobelev

Reputation: 10557

Recommendation #1: You need to read your book completely.

It is not true that in case of every error you should throw an exception. Exception should happen something less often that every 1000 calls to your function/method. 1000 is not a magic value here, in particular case other number might be appropriate.

In other words. The first question that you need to answer: how often this error may happen. If this may happen often, then the return value (bool or enum or int) is a better approach.

If you decided to use exception, it is better to derive it from std::exception. You should place exceptions of your project in a separate file. Think about a couple of classes, maybe 3-10. It is better to place a data field inside your exception class that should explain details of what happened instead of creating hundreds of different exception classes.

Upvotes: 6

charly
charly

Reputation: 956

the exception class can be in a separate .h .cpp file. That way you can reuse for something else.

As my own rule of thumb:

assertions are for things that should never happen but we check just to be sure 100% sure

Exceptions is for error handling things that can happen when your program is in production

Upvotes: 1

tomahh
tomahh

Reputation: 13651

C++ standard library provides many exception class that you can use. For begining, you can use them. In your case, what applies seems to be range error.
If you still want to implement your own exception class, where you declare and implement it should depend on what they code for. If they code for a class specific error, you can put them in your class file. If you have to use them from multiple files, put them in they own .cpp/.hpp couple.

Upvotes: 0

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