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| -rw-r--r-- | indra/newview/tests/cppfeatures_test.cpp | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/indra/newview/tests/cppfeatures_test.cpp b/indra/newview/tests/cppfeatures_test.cpp index 67671dc65e..bfaa83140d 100644 --- a/indra/newview/tests/cppfeatures_test.cpp +++ b/indra/newview/tests/cppfeatures_test.cpp @@ -247,5 +247,94 @@ void cpp_features_test_object_t::test<7>() ensure("default copy d3", d.val()==d3.val()); } +// initialize class members inline +// +// https://en.cppreference.com/w/cpp/language/data_members#Member_initialization +// +// Default class member values can be set where they are declared, using either brackets or = + +// It is preferred to skip creating a constructor if all the work can be done by inline initialization: +// http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines.html#c45-dont-define-a-default-constructor-that-only-initializes-data-members-use-in-class-member-initializers-instead +// +class InitInline +{ +public: + S32 mFoo{10}; +}; + +class InitInlineWithConstructor +{ +public: + // Here mFoo is not specified, so you will get the default value of 10. + // mBar is specified, so 25 will override the default value. + InitInlineWithConstructor(): + mBar(25) + {} + + // Default values set using two different styles, same effect. + S32 mFoo{10}; + S32 mBar = 20; +}; + +template<> template<> +void cpp_features_test_object_t::test<8>() +{ + InitInline ii; + ensure("init member inline 1", ii.mFoo==10); + + InitInlineWithConstructor iici; + ensure("init member inline 2", iici.mFoo=10); + ensure("init member inline 3", iici.mBar==25); +} + +// constexpr +// +// https://en.cppreference.com/w/cpp/language/constexpr +// +// Various things can be computed at compile time, and flagged as constexpr. +constexpr S32 compute2() { return 2; } + +constexpr S32 ce_factorial(S32 n) +{ + if (n<=0) + { + return 1; + } + else + { + return n*ce_factorial(n-1); + } +} + +template<> template<> +void cpp_features_test_object_t::test<9>() +{ + S32 val = compute2(); + ensure("constexpr 1", val==2); + + // Compile-time factorial. You used to need complex templates to do something this useless. + S32 fac5 = ce_factorial(5); + ensure("constexpr 2", fac5==120); +} + +// static assert +// +// https://en.cppreference.com/w/cpp/language/static_assert +// +// You can add asserts to be checked at compile time. The thing to be checked must be a constexpr. +// There are two forms: +// * static_assert(expr); +// * static_assert(expr, message); +// +// Currently only the 2-parameter form works on windows. The 1-parameter form needs a flag we don't set. + +template<> template<> +void cpp_features_test_object_t::test<10>() +{ + // static_assert(ce_factorial(6)==720); No, needs a flag we don't currently set. + static_assert(ce_factorial(6)==720, "bad factorial"); // OK +} + + } // namespace tut |