title: Extending the .NET MembershipUser with own properties
body: <p>I've written a custom <code>MembershipProvider</code> that works really great except one little thing, I'd like to extend the <code>MembershipUser</code> class a bit.</p>
  
  <p>The default looks like this:</p>
  
  <pre><code>MembershipUser member = new MembershipUser(
      providerName: Membership.Provider.Name,
      name: db.userName,
      providerUserKey: null,
      email: db.userEmail,
      passwordQuestion: "",
      comment: "",
      isApproved: true,
      isLockedOut: false,
      creationDate: db.creationDate,
      lastLoginDate: db.lastLoginDate,
      lastActivityDate: db.lastActivityDate,
      lastPasswordChangedDate: DateTime.Now,
      lastLockoutDate: DateTime.Now
      );
  </code></pre>
  
  <p>But I'd like to extend it a bit, something like this:</p>
  
  <pre><code>MembershipUser member = new MembershipUser(
      providerName: Membership.Provider.Name,
      name: db.userName,
      guid: db.userGuid,
      company: db.companyName,
      companyGuid: db.companyGuid,
      whatever: db.whatever,
      providerUserKey: null,
      email: db.userEmail,
      passwordQuestion: "",
      comment: "",
      isApproved: true,
      isLockedOut: false,
      creationDate: db.creationDate,
      lastLoginDate: db.lastLoginDate,
      lastActivityDate: db.lastActivityDate,
      lastPasswordChangedDate: DateTime.Now,
      lastLockoutDate: DateTime.Now
      );
  </code></pre>
  
  <p>Is there a way to extend the default class?</p>