c# - Implicit (bool) and == operator override - handle if statements correctly -

i have custom class implement both == , implicit boolean operator.

is correct way handle possible, if ==/!= statements , expected result? this:

public class foo {     public bool result { get; set; }      public static bool operator ==(bool @bool, foo foo)     {         return equals(foo, @bool);     }     public static bool operator !=(bool @bool, foo foo)     {         return notequals(foo, @bool);     }     public static bool operator ==(foo foo, bool @bool)     {         return equals(foo, @bool);     }     public static bool operator !=(foo foo, bool @bool)     {         return notequals(foo, @bool);     }     public static bool operator ==(foo foo, foo foob)     {         return equals(foo, foob);     }     public static bool operator !=(foo foo, foo foob)     {         return notequals(foo, foob);     }     public static implicit operator bool(foo foo)     {         try { return foo.result; }         catch { return false; }     }      private static bool equals(foo foo, foo foob)     {         if (object.equals(foo, null))         {             if (object.equals(foob, null))                 return true;              return false;         }          if (object.equals(foob, null))             return false;          return foo.result == foob.result;     }     private static bool notequals(foo foo, foo foob)     {         if (object.equals(foo, null))         {             if (object.equals(foob, null))                 return false;              return true;         }          if (object.equals(foob, null))             return true;          return foob.result != foo.result;     }     private static bool equals(foo foo, bool @bool)     {         if (object.equals(foo, null))             return true;          return @bool == foo.result;     }     private static bool notequals(foo foo, bool @bool)     {         if (object.equals(foo, null))             return false;          return @bool != foo.result;     }  } 

i wondering fact seems need implement overloads either

if (new foo() != true) 

and

if (true != new foo()) 

i think you've written code :-)

the following sufficient:

public class foo {     public bool result { get; set; }      public static implicit operator bool(foo foo)     {         return !object.referenceequals(foo, null) && foo.result;     } } 

the compiler know how implicitly convert variables of type foo bool. (and null converted false).

so, when write:

new foo() == false 

the compiler use implicit type converter bool value foo , use standard equality operator bool.

if @ il compiler generates expression find:

newobj instance void foobool.foo::.ctor()               // new foo() call bool foobool.foo::op_implicit(class foobool.foo)   // implicit operator (foo => bool) ldc.i4.0                                                // false ceq                                                     // equality operator (bool) 

here's test:

static void main(string[] args) {     asserttrue(new foo() == false);     asserttrue(false == new foo());     assertfalse(new foo() != false);     assertfalse(false != new foo());     asserttrue(new foo { result = true } == true);     asserttrue(true == new foo { result = true });     assertfalse(new foo { result = true } != true);     assertfalse(true != new foo { result = true }); }  static void asserttrue(bool value) {     console.writeline(value ? "ok" : "not ok"); }  static void assertfalse(bool value) {     console.writeline(value ? "not ok" : "ok"); } 

it prints ok each test. simplified code should fulfill needs if understood them correctly.

update

to allow equality operator work instances of foo (which may null):

public static bool operator ==(foo a, foo b) {     if (object.referenceequals(a, b))     {         return true;     }     else if (object.referenceequals(a, null))     {         return !b.result;     }     else if (object.referenceequals(b, null))     {         return !a.result;     }     else     {         return a.result == b.result;     } } 

you should implement inequality operator:

public static bool operator !=(foo a, foo b) {     return !(a == b); } 

and override gethashcode + equals

public override int gethashcode() {     return this.result ? 1 : 0; }  public override bool equals(object obj) {     if (object.referenceequals(obj, null))     {         return !this.result;     }      type t = obj.gettype();      if (t == typeof(foo))     {         return this.result == ((foo)obj).result;     }     else if (t == typeof(bool))     {         return this.result == (bool)obj;     }     else     {         return false;     } }