C++ mark as deprecated

c++

Question

I have a method in an interface that I want to deprecate with portable C++. When I Googled for this all I got was a Microsoft specific solution; #pragma deprecated and __declspec(deprecated).

A second prize solution would be to ifdef a MSVC and a GCC solution.
Thanks

1
137
3/20/2019 5:34:18 PM

Accepted Answer

In C++14, you can mark a function as deprecated using the [[deprecated]] attribute (see section 7.6.5 [dcl.attr.deprecated]).

The attribute-token deprecated can be used to mark names and entities whose use is still allowed, but is discouraged for some reason.

For example, the following function foo is deprecated:

[[deprecated]]
void foo(int);

It is possible to provide a message that describes why the name or entity was deprecated:

[[deprecated("Replaced by bar, which has an improved interface")]]
void foo(int);

The message must be a string literal.

For further details, see “Marking as deprecated in C++14”.

168
9/15/2014 10:16:43 AM

This should do the trick:

#ifdef __GNUC__
#define DEPRECATED(func) func __attribute__ ((deprecated))
#elif defined(_MSC_VER)
#define DEPRECATED(func) __declspec(deprecated) func
#else
#pragma message("WARNING: You need to implement DEPRECATED for this compiler")
#define DEPRECATED(func) func
#endif

...

//don't use me any more
DEPRECATED(void OldFunc(int a, float b));

//use me instead
void NewFunc(int a, double b);

However, you will encounter problems if a function return type has a commas in its name e.g. std::pair<int, int> as this will be interpreted by the preprocesor as passing 2 arguments to the DEPRECATED macro. In that case you would have to typedef the return type.

Edit: simpler (but possibly less widely compatible) version here.


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