Even if there were a common consensus, it wouldn't mean it is valid. Your primary consideration here should be the implementation and performance costs. These are both real constraints on the project and the resulting program. In this respect, here are some things to consider.
At runtime, exceptions are more expensive to propagate than simple return values. This is usually the source of the in exceptional cases argument. If you are throwing a lot of exceptions all the time you are suffering a performance penalty. Don't take this to mean exceptions are slow, they are still implemented very efficiently, but nonetheless costlier than error codes.
Exceptions can carry more information than error codes. Something like the boost::exception
library allows tagged information which can provide a wealth of useful information up the chain of the exception. Unlike a simple error code saying file not found an exception can carry the filename, the module that tried to load it, and of course the underlying error code. This type of information is very hard to propagate via error codes up the stack.
Error code propagation can be cumbersome at implementation time. Any function that doesn't want to deal with an error has to pass the value up higher. Quite often you'll find code that simply ignores the error since the programmer couldn't deal with it at the time, or he didn't want to refactor his function signatures to pass along the error.
Exception catch
syntax is bulky. It is often far easier to check a return code in an if
statement than having to write a catch
block. If a function has to catch too many differing exceptions at different points, the meaning of the code will be lost in a sea of braces and try/catch clauses. Here is the likely root of the notion that if a function call can normally fail a return code is likely better than an exception.
Understanding clearly how exceptions work will help you in making a decision. There are performance considerations but for many projects this will be negligible. There are concerns about exception safety, you have to know where it is safe and unsafe to use exceptions. Error codes also have the same safety concerns if people start doing short returns from functions.
Understanding the background of your team can also help out; consider if you have two new C++ programmers, one from a C background and the other coming from Java. Some people are more comfortable with error codes, others with exceptions. How far you push either in each direction will impact your project and contribute to the overall quality.
In the end there is no clear answer. While there are some situations where one may clearly win over the other, it highly depends on the project. Look at your code and continue to refactor when appropriate. Sometimes you won't even have an option as to what you use. Other times it'll make no difference. It is highly project specific.