I have an IPredicate instance passed into a method. I have no idea what is it or where it came from. I need to clone it - how can I do this?

Why to clone it, just copy it. It holds no state info or identity to change.

IPredicateExpression filter = new PredicateExpression(CustomerFields.Country == "UK");
filter.AddWithAnd(CustomerFields.City == "London");
var filter2 = new PredicateExpression(filter);

filter2.AddWithOr(CustomerFields.Country == "Germany");
filter2.AddWithOr(CustomerFields.Country == "USA");

filter will hold none of the predicates added to filter2.

I get very confused with this but I think you are referring to IPredicateExpression instances whereas I only have an IPredicate - ie the result of [CustomerFields.Country == "UK"]

My intention after cloning was to invert its Negate property (so it does have state) and then use it elsewhere. So I don't think it would work.

Anyway, I now think I need to put the IPredicate into an IPredicateExpression and Negate that instead. I found GeneralUtils.CreateUsablePredicateExpressionClone() but I will try your new PredicateExpression(filter) since that looks simpler.

Thanks.