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#include <iostream>
#include <string>
struct member
{
member( const std::string& value, const std::string& name, const std::string& held_by )
: value(value), member_name(name), containing_object_name(held_by) {}
std::string value ;
const std::string member_name ;
const std::string containing_object_name ;
member& operator= ( const member& that )
{
static int n = 0 ;
std::cout << ++n << ". "
<< this->containing_object_name << '.' << this->member_name << " = "
<< that.containing_object_name << '.' << that.member_name << '\n' ;
value = that.value ;
return *this ;
}
};
struct holder
{
holder( const char* holder_name, const char* a, const char* b, const char* c )
: one( a, "one", holder_name ),
two( b, "two", holder_name ),
three( c, "three", holder_name ) {}
member one ;
member two ;
member three ;
// *** the class does not have a user-defined assignment operator ***
// *** the semantics of implicitly defined assignment is member-wise assignment
// *** ie. assign members one by one in the order of declaration
};
int main()
{
holder lhs( "lhs", "a", "b", "c" ) ;
const holder rhs( "rhs", "dd", "eee", "ffff" ) ;
std::cout << "value of members before assignment: " << lhs.one.value << ',' << lhs.two.value << ','
<< lhs.three.value << "\n\n" ; // value of members before assignment: a,b,c
// assign rhs to lhs using the implicitly defined assignment operator
lhs = rhs ; // this performs member-wise assignment
// ie. assign members of rhs to the corresponding members in lhs
// in the order of declaration of the members
// 1. lhs.one = rhs.one
// 2. lhs.two = rhs.two
// 3. lhs.three = rhs.three
std::cout << "\nvalue of members after assignment: " << lhs.one.value << ',' << lhs.two.value << ','
<< lhs.three.value << '\n' ; // value of members after assignment: dd,eee,ffff
}
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