Re: safe alternative to va_arg

Fabian wrote:
for my error handling I have a class with static method overloads to print
error messages (I will probably make this a bit more general with some
pattern later). But for the start it is enough to print messages with
different numbers of arguments. I don't want to write endless overloads
for different numbers of arguments. So my first design looks like this:
[..]
class ErrorHandler
{
public:
static inline void PrintError(const char* source, const int& numMsgParams,
...);
private:
explicit ErrorHandler(){};
};

A few things up front:
1. Passing 'int' by reference is overkill. The typical implementation of
references is to pass a pointer, which might even be larger than just
passing the integer itself and it incurs the indirection overhead.
2. Not every '}' is followed by a ';'!
3. ErrorHandler::PrintError() - I'd remove at least one instance of 'Error'
here.
4. Classes that only have static functions are conveniently replaced with
namespaces.


Anyway, back to the issue you actually came for, instead of adding various
overloads, use templates:

// no arguments
void print( char const* msg);
// one argument
template<typename A1>
print( char const* msg, A1 const& a1);
// two arguments
template<typename A1, typename A2>
print( char const* msg, A1 const& a1, A2 const& a2);

This is still some writing, but it's not that much, and how many additional
arguments do you need anyway?

Take a look at Boost.Format, btw!

Uli

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