2fd1f00f1dd2d4dadcc3c350165e2c0faee69c9b
angie
  Wed Jan 5 09:22:23 2011 -0800
Keep the multShadow vars in the cart so that we can distinguish alist that has been set to empty from a list that has never been
set.  cartListVarExists is the external interface.

diff --git src/hg/inc/cart.h src/hg/inc/cart.h
index b058e97..1648b7b 100644
--- src/hg/inc/cart.h
+++ src/hg/inc/cart.h
@@ -89,30 +89,33 @@
 struct slPair *cartVarsLike(struct cart *cart, char *wildCard);
 /* Return a slPair list of cart vars that match the wildcard */
 
 struct slPair *cartVarsWithPrefix(struct cart *cart, char *prefix);
 /* Return a slPair list of cart vars that begin with prefix */
 
 void cartRemoveLike(struct cart *cart, char *wildCard);
 /* Remove all variable from cart that match wildCard. */
 
 void cartRemovePrefix(struct cart *cart, char *prefix);
 /* Remove variables with given prefix from cart. */
 
 boolean cartVarExists(struct cart *cart, char *var);
 /* Return TRUE if variable is in cart. */
 
+boolean cartListVarExists(struct cart *cart, char *var);
+/* Return TRUE if a list variable is in cart (list may still be empty). */
+
 INLINE boolean cartVarExistsDb(struct cart *cart, char *db, char *var)
 /* Return TRUE if variable_$db is in cart. */
 {
 return cartVarExists(cart, _cartVarDbName(db, var));
 }
 
 char *cartString(struct cart *cart, char *var);
 /* Return string valued cart variable. */
 
 INLINE char *cartStringDb(struct cart *cart, char *db, char *var)
 /* Return string valued cart var_$db. */
 {
 return cartString(cart, _cartVarDbName(db, var));
 }