Generic functions and ref returns in C# 7.0 -

is possible use ref returns feature in c# 7.0 define generic function can both comparison , update of field in 2 instances of object? imagining this:

void updateifchanged<tclass, tfield>(tclass c1, tclass c2, func<tclass, tfield> getter) {     if (!getter(c1).equals(getter(c2))     {         getter(c1) = getter(c2);     } } 

example intended usage:

thing thing1 = new thing(field1: 0, field2: "foo"); thing thing2 = new thing(field1: -5, field2: "foo"); updateifchanged(thing1, thing2, (thing t) => ref t.field1); updateifchanged(thing1, thing2, (thing t) => ref t.field2); 

is there way specify func type or kind of generic type restriction make valid requiring getter return reference? tried func<tclass, ref tfield>, doesn't appear valid syntax.

you won't able use func, because doesn't return result reference. you'll need create new delegate uses ref return:

public delegate ref tresult refreturningfunc<tparameter, tresult>(tparameter param); 

then changing function use delegate enough work:

public static void updateifchanged<tclass, tfield>(tclass c1, tclass c2, refreturningfunc<tclass, tfield> getter) {     if (!getter(c1).equals(getter(c2)))     {         getter(c1) = getter(c2);     } } 

note property cannot returned reference. return field reference, or other variable, property not variable.