In various places in code we want to use property names in our
code, for instance validation or business rules are quick commonly
named after the property they're validating. Usually you end up with
code looking a little like this.
Rule<Person> rule = new Rule<Person>("FirstName");
As Ayende
says "Strings are bad", there are typo issues and also they're immune
to refactoring. So here's a quick way not to use them, I wouldn't call
this fully fledged as we're not getting compile time checking yet. The
key part to this code is taking an Expression rather than a Func, this
allows us to examine the expressions in the lambda to get the property
name.
public class Rule<T>
{
private string name;
public Rule(Expression<Func<T, object>> expression)
{
MemberExpression memberExpression = expression.Body as MemberExpression;
name = memberExpression == null ? String.Empty : memberExpression.Member.Name;
}
public string Name
{
get
{
return name;
}
}
}
This gives the syntax for rule creation as follows.
Rule<Person> rule = new Rule<Person>(p => p.FirstName);
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