equality

class L(object): def __eq__(self, other): print 'invoked L.__eq__' return False class R(object): def __eq__(self, other): print 'invoked R.__eq__' return False left = L() right = R() With this code, left side gets the first shot at comparison, as documented in the data model: >>> left == right invoked L.__eq__ False But if we make a slight modification on line 6 (everything else the same): class R(L): Now the right side gets to have the first shot at comparison. >>> left == right invoked R.__eq__ False Why is that? Where is it documented, and what's the reason for the design decision? This is

I know that identical objects are not equal, i.e: var obj = { name: "Value" }; var obj2 = { name: "Value" }; console.log("obj equals obj2: " + (obj === obj2)); //evaluates to false Yet primitive types are: var str = "string1"; var str2 = "string1"; console.log("str equals str2: " + (str === str2)); //evaluates to true My question is why. Why are objects and primitives treated differently? If an object is nothing but an empty container, with only the attributes you specify to put in the container, why wouldn't the container's identical attributes evaluate to be the same? I looked around for

Say I have an object Person with the properties below: public class Person { public int ID { get; set; } public int EmployeeNo { get; set; } public string JobDescription { get; set; } public string Code { get; set; } } How would I dynamically check the equality of specific properties by name? eg. var dynamicEqualityComparer = RetrieveDynamicEqualityComparer("ID", "JobDescription"); var intersectedPersons = listOfPerson1.Intersect(listOfPerson2, dynamicEqualityComparer); The above snippit would use the default linq intersect method using the dynamically generated equality comparison method

This question already has an answer here: How to test multiple variables against a value? 23 answers I have a variable, and want to check if it matches at least one of the other two variables. Clearly I can do: if a == b or a == c: But I want to know if there is any shorter way, something like: if a == (b or c): How to test if a variable is the same as - at least - one of the others? sshashank124 For that use in : if a in (b, c): Testing for membership in a tuple has an average case of O(n) time complexity. If you have a large collection of values and are performing many membership tests on

I need to define a method to compare two different objects of a same type. The type of objects is not specific. The objects may be a DLL type, so I can't override Equals method. I have to do this by reflection. This code works if all the members of objects are of primitive type. But it doesn't work when an object has a field that isn't primitive. How can I do it by reflection? public bool Equals(object obj1, object obj2) { List<FieldInfo> fieldInfos = obj1.GetType().GetFields().ToList(); return (fieldInfos.Select(fieldInfo => new {fieldInfo, type = fieldInfo.GetType()}) .Where(@t => @t.type