Is argument-dependent lookup the only way val() can be found? Yes, it is the only way. To quote the holy standard at [namespace.memdef]/3: If a friend declaration in a non-local class first declares a class, function, class template or function template the friend is a member of the innermost enclosing namespace. The friend declaration does … Read more
const date& being accepted by the method date_ok means that date_ok takes a reference of type const date. It works similar to pointers, except that the syntax is slightly more .. sugary in your example, int* Y = &x makes Y a pointer of type int * and then assigns it the address of x. … Read more
Note: You might want to look at the operator overloading FAQ. Binary operators can either be members of their left-hand argument’s class or free functions. (Some operators, like assignment, must be members.) Since the stream operators’ left-hand argument is a stream, stream operators either have to be members of the stream class or free functions. … Read more
It is explicitly disallowed in the standard, even if some versions of VisualStudio do allow it. C++ Standard 7.1.5.3 Elaborated type specifiers, paragraph 2 3.4.4 describes how name lookup proceeds for the identifier in an elaborated-type-specifier. If the identifier resolves to a class-name or enum-name, the elaborated-type-specifier introduces it into the declaration the same way … Read more
Friendship is not inherited in C++. The standard says (ISO/IEC 14882:2003, section 11.4.8): Friendship is neither inherited nor transitive.
There is a way to read unexported members using reflect (in Go < 1.7) func read_foo(f *Foo) { v := reflect.ValueOf(*f) y := v.FieldByName(“y”) fmt.Println(y.Interface()) } However, trying to use y.Set, or otherwise set the field with reflect will result in the code panicking that you’re trying to set an unexported field outside the package. … Read more
Thanks to your other question it looks like this pattern is now known as the “passkey” pattern. In C++11, it gets even cleaner, because instead of calling b.protectedMethod(SomeKey()); you can just call: b.protectedMethod({});
C++ Standard ISO/IEC 14882:2003(E) 7.3.1.2 Namespace member definitions Paragraph 3 Every name first declared in a namespace is a member of that namespace. If a friend declaration in a non-local class first declares a class or function (this implies that the name of the class or function is unqualified) the friend class or function is … Read more
Try this (straight from Google Test docs…): FRIEND_TEST(TestCaseName, TestName); For example: // foo.h #include <gtest/gtest_prod.h> // Defines FRIEND_TEST. class Foo { … private: FRIEND_TEST(FooTest, BarReturnsZeroOnNull); int Bar(void* x); }; // foo_test.cc … TEST(FooTest, BarReturnsZeroOnNull) { Foo foo; EXPECT_EQ(0, foo.Bar(NULL)); // Uses Foo’s private member Bar(). }
It sounds like you want to change: friend ostream& operator << (ostream& out, const Base<T>& e); To: template<class T> friend ostream& operator << (ostream& out, const Base<T>& e);