c# - Is it a code smell to return a delegate that leaks implementation details? -

i have class called mapbuilder<t> internally uses dictionary<propertyinfo,string> class used build mapping of properties proxied. class looks this::

public class mapbuilder<t>{     private dictionary<propertyinfo, string> m_map = new dictionary<propertyinfo,string>();      public mapbuilder<t> add<tproperty>(expression<func<t, tproperty>> property){         argumentvalidator.assertisnotnull(()=>property);         var propertyinfo = reflect.property<t>.infoof(property);         m_map.add(propertyinfo, propertyinfo.name);         return this;     }      public mapbuilder<t> add<tproperty>(expression<func<t, tproperty>> property,string columnname){         argumentvalidator.assertisnotnull(() => property);         argumentvalidator.assertisnotnull(() => columnname);         var propertyinfo = reflect.property<t>.infoof(property);         m_map.add(propertyinfo, columnname);         return this;     }      public map compile(){         return m_map.trygetvalue;     } 

so user use so::

 var map= new mapbuilder<myclass>() .add(x => x.name) .add(x => x.id) .add(x => x.active) .compile() 

which build map encapsulates 3 properties of name,id,active. problem map delegate can leak implementation detail end user because can observe method trygetvalue method of dictionary<propertyinfo,string> , target private dictionary. consider code smell?

i can wrap in anonymous method, tend consider bad form when method group conversion possible.

the level of effort involved in looking @ target , method of map delegate same reflecting on fields of mapbuilder class itself; either way, caller can discover private dictionary instance.

i wouldn't worry point of view of mapbuilder class. reflecting on private fields code smell: it's not responsibility, responsibility of user of class.