assignment-operator

I have an "Event" class. Due to the way dates are handled, we need to wrap this class in a "UIEvent" class, which holds the Event, and the date of the Event in another format. What is the best way of allowing conversion from Event to UIEvent and back? I thought overloading the assignment or copy constructor of UIEvent to accept Events (and vice versa)might be best. There are two simple options that I can think of. The first option would be the one you describe: create a constructor that takes an object of the other type: struct UIEvent { UIEvent(const Event&); }; and use std::copy to copy

When defining an assignment operator, it invariably looks like this: class X {...}; X& X::operator=(...whatever...); That is, it has the return type "reference to X". Here, parameters ( ...whatever... ) can be X& , const X& , just X when using the copy-and-swap idiom , or any other type. It seems strange that everyone recommends returning a non-const reference to X , regardless of the parameters. This explicitly allows expressions like (a = b).clear() , which is supposed to be good. I have a different opinion, and I want to disallow expressions like (x=y).clear , (x=y)=z , and even x=y=z in my

I have a large data frame and I am trying to assign values to a particular data column for specific subsets. subset(P2Y12R_binding_summary,(SYSTEM=="4NTJ")&(VARIANT=="D294N")) SYSTEM VARIANT MODEL EPSIN INP dE_water_free dE_ERR_water_free dE_water_periodic dE_ERR_water_periodic 1 4NTJ D294N LVLSET 1 1 -42.155 29.28460 -42.205 29.52604 2 4NTJ D294N LVLSET 1 2 -34.225 29.75176 -34.235 29.96571 3 4NTJ D294N LVLSET 20 1 -65.163 40.62241 -65.163 40.52564 4 4NTJ D294N LVLSET 20 2 -57.454 41.04459 -57.454 41.26962 5 4NTJ D294N SES 1 1 -23.406 30.56636 -23.335 30.75794 6 4NTJ D294N SES 1 2 -15.434 30

Let's just take for example the specific compound assignment operator ^= . This stackoverflow page says modification of the left operand may have not been done after the evaluation of ^= , and thus making the code a ^= b ^= a ^= b undefined behaivor. But this does not seem to be the case. The standard says in 5.17 [expr.ass] that In all cases, the assignment is sequenced after the value computation of the right and left operands, and before the value computation of the assignment expression. There are two keypoints in this statement. 1) What does the subject assignment refers to? In my opinion

I am defining multiple overloads of the assignment operator as follows: Foo.h class Foo { private: bool my_bool; int my_int; std::string my_string; public: Foo& operator= (bool value); Foo& operator= (int value); Foo& operator= (const std::string& value); }; Foo.cpp // Assignment Operators. Foo& Foo::operator= (bool value) {my_bool = value; return *this;} Foo& Foo::operator= (int value) {my_int = value; return *this;} Foo& Foo::operator= (const std::string& value) {my_string = value; return *this;} And here's my main.cpp (see the comment marked SURPRISE ): Foo boolFoo; Foo intFoo; Foo

Python 3.2.3 (default, Apr 11 2012, 07:15:24) [MSC v.1500 32 bit (Intel)] on win 32 Type "help", "copyright", "credits" or "license" for more information. >>> u = [4, 5, 6, 7, 8, 9] >>> u[1::1] = [3, 2, 1, 0] >>> u [4, 3, 2, 1, 0] >>> u[9:0:-1] = [8, 7, 6, 5] >>> u [4, 5, 6, 7, 8] >>> u[9:0:-1] = [16, 12, 8] Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: attempt to assign sequence of size 3 to extended slice of size 4 >>> u [4, 5, 6, 7, 8] >>> Expected behaviour: no exception thrown on final assignment statement; u should print on final line as [4, 8, 12, 16