I hate having a bunch of "left/right" methods. Every time a property is added or removed, I have to fix up each method. And the code itself just looks ... wrong.
public Foo(Foo other)
{
this.Bar = other.Bar;
this.Baz = other.Baz;
this.Lur = other.Lur;
this.Qux = other.Qux;
this.Xyzzy= other.Xyzzy;
}
Really this is just an unrolled loop that iterates through the properties, copying them between objects. So why not be honest about that fact? Reflection to the rescue!
public Foo(IFoo other)
{
foreach (var property in typeof(IFoo).GetProperties())
{
property.SetValue(this, property.GetValue(other, null), null);
}
}
I may just be trying to force a paradigm I learned from Lua onto C#, but this particular example doesn't seem too smelly to me. From here, I started to do some more complex things that were sensitive to the order of the fields. For example, rather than having a stack of virtually identical if
statements to compose a string from the fields, I just iterate over them in the desired order:
public override string ToString()
{
var toJoin = new List<string>();
foreach (var property in tostringFields)
{
object value = property.GetValue(this, null);
if (value != null)
toJoin.Add(value.ToString());
}
return string.Join(" ", toJoin.ToArray());
}
private static readonly PropertyInfo[] tostringFields =
{
typeof(IFoo).GetProperty("Bar"),
typeof(IFoo).GetProperty("Baz"),
typeof(IFoo).GetProperty("Lur"),
typeof(IFoo).GetProperty("Qux"),
typeof(IFoo).GetProperty("Xyzzy"),
};
So now I have the iterability I wanted, but I still have stacks of code mirroring each property I'm interested in (I'm also doing this for CompareTo, using a different set of properties in a different order). Worse than that is the loss of strong typing. This is really starting to smell.
Well what about using attributes on each property to define the order? I started down this road and indeed it worked well, but it just made the whole thing look bloated. It works great semantically, but I'm always wary of using advanced features just because they're "neat." Is using reflection in this way overkill? Is there some other solution to the left/right code problem I'm missing?