I am unable to use Google Test's ASSERT_THROW()
macro in combination with multiple template arguments. Consider that I want to make sure that construction of Matrix<5,1>
throws:
ASSERT_THROW(Matrix<5,1>(), std::runtime_error);
(this example doesn't make a lot of sense, of course this shoud not throw, but it is what stayed after simplifying what I had.)
I get this output from MS VC++ 2008:
warning C4002: too many actual parameters for macro 'ASSERT_THROW' error C2143: syntax error : missing ',' before ';'
Whereas there are no problems with:
ASSERT_THROW(Matrix<1>(), std::runtime_error);
How can I overcome this problem?
Thanks!
In C++ this can be achieved using template parameters. A template parameter is a special kind of parameter that can be used to pass a type as argument: just like regular function parameters can be used to pass values to a function, template parameters allow to pass also types to a function.
A lot of Excel users are confused about when to use macros and when to create templates. A macro is a recording of formatting changes and other steps that can be replayed quickly. A template is a pre-formatted spreadsheet with headers and formulas – awaiting your data.
Template classes and functions can make use of another kind of template parameter known as a non-type parameter. A template non-type parameter is a template parameter where the type of the parameter is predefined and is substituted for a constexpr value passed in as an argument.
Function-like macros can take arguments, just like true functions. To define a macro that uses arguments, you insert parameters between the pair of parentheses in the macro definition that make the macro function-like. The parameters must be valid C identifiers, separated by commas and optionally whitespace.
the problem is the extra comma, you will need to protect it from the macro. Try
ASSERT_THROW((Matrix<5,1>()), std::runtime_error);
#define COMMA , ASSERT_THROW(Matrix<5 COMMA 1>(), std::runtime_error);
Edit: @tletnes answer is simpler, however this one will work even if the macro parameter used as a non-expression. For example:
BOOST_FOREACH(std::pair<int COMMA int>& v, myVec) { } // works BOOST_FOREACH((std::pair<int, int>)& v, myVec) { } // fails
More edit: The macro COMMA is already defined in boost:
#include <boost/preprocessor/punctuation/comma.hpp> ASSERT_THROW(Matrix<5 BOOST_PP_COMMA() 1>(), std::runtime_error); BOOST_FOREACH(std::pair<int BOOST_PP_COMMA() int>& v, myVec) { }
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