C++ Exception Specification for overloaded functions

Question

class ESClass
{
public:
    void PrintMe() throw();
    void PrintMe(int) throw(int);
};

I want to know whether or not we can define different exception specification for overloaded functions. In other words, can we give different exception specification to different version of the function PrintMe?

Note from VS2010:

warning C4290: C++ exception specification ignored except to indicate a function is not __declspec(nothrow)

I suggest you read this: gotw.ca/publications/mill22.htm. To cut to the chase, " Moral #1: Never write an exception specification. Moral #2: Except possibly an empty one, but if I were you I’d avoid even that." — Fred Larson
– Fred Larson, Commented Aug 11, 2011 at 20:02
The visual studio warning has been there forever. This is not the only situation in which it warns you against complying to the C++ standard. — André Caron
– André Caron, Commented Aug 11, 2011 at 20:02
I think Fred wanted you to read it up to the point where it says "So here’s what seems to be the best advice we as a community have learned as of today: Moral #1: Never write an exception specification. Moral #2: Except possibly an empty one, but if I were you I’d avoid even that." — André Caron
– André Caron, Commented Aug 11, 2011 at 20:07
@q0987 - It isn't about overloaded functions, it is about using exception specifications at all with VC++. The compiler only handles throw() and nothing else. — Bo Persson
– Bo Persson, Commented Aug 11, 2011 at 20:07

Community · Accepted Answer · 2017-05-23 12:00:17Z

9

Yes: they are different functions, they can have different exception specifications.

If a virtual member function has an exception specification, any override (not overload) must have an exception specification that is at least as strict as the member function being overridden.

Of course, you should "never write an exception specification" except in those few situations where you must.

Visual C++ does not fully support exception specifications, so it allows some code that is not actually valid per the C++ language specification. The warning you mention just means that you are using code that uses a C++ language feature not supported by Visual C++:

A function is declared using exception specification, which Visual C++ accepts but does not implement. Code with exception specifications that are ignored during compilation may need to be recompiled and linked to be reused in future versions supporting exception specifications.

edited May 23, 2017 at 12:00

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answered Aug 11, 2011 at 20:01

James McNellis

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8 Comments

André Caron Over a year ago

Although it is legal, it's a bad habit to throw different sets of exceptions from different overloads. It's easy to forget to update the catch clauses when only changing the arguments passed to the function...

pmr Over a year ago

What is the meaning of "strictness" in regard to exception specifications?

James McNellis Over a year ago

@pmr: "If a virtual function has an exception-specification, all declarations, including the definition, of any function that overrides that virtual function in any derived class shall only allow exceptions that are allowed by the exception-specification of the base class virtual function (C++03 §15.4/3)." So, an override can have a stricter exception specification, meaning it allows fewer exceptions to be thrown.

q0987 Over a year ago

@pmr, 'strictness' means that you are ONLY allowed to specify same type or subtype of the original exception specification type.

James McNellis Over a year ago

@AntonK: If you're asking whether we plan to implement full support for dynamic exception specifications, I expect the answer is "probably not." Dynamic exception specifications are deprecated in C++11.

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