Specifying Allowed Template Classes
Is there any way to specify classes you would allow a template to be used for?
For example, I want to allow about 3 (int, float, char) data types to be used for this one class, as what it does would be identical for all those types, so naturally I think template, however, I don't want other data types, like user defined classes to be passed in that would potentially cause errors.
You can create a template on generic type T that causes a compile error. Then specialize the template for float, int and char so that it doesn't cause a compile error.
Alexandrescu has more information in his Modern C++ Design book and Loki library.
Also, template specialization is discussed here: http://www.parashift.com/c++-faq-lit....html#faq-35.7 and in the next couple entries.
You could use boost's StaticAssert library to force the compiler error. http://boost.org/doc/html/boost_staticassert.html (see the examples at the bottom).
Look at boost::enable_ifOriginally Posted by nine-hundred
If the template wont compile for some classes then that will already stop people from being able to use your template with those classes.
On the other hand, if it does work then who are you to say that the user of the template shouldn't be allowed to use it like that?
If the reason for this is that your class makes certain assumptions, that might compile fine but just not work, then the correct thing to do is to add some compile-time assertions to cover those assumptions. Look into C_ASSERT.
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