0
@@ -184,8 +184,14 @@ extern id Nu__null;
0
     id value = Nu__null;
0
 
0
     // if the macro contains gensyms, give them a unique prefix
0
-    id bodyToEvaluate = ([[self gensyms] count] == 0)
0
-        ? (id)body : [self body:body withGensymPrefix:[NSString stringWithFormat:@"g%ld", [NuMath random]] symbolTable:symbolTable];
0
+    int gensymCount = [[self gensyms] count];
0
+    id gensymPrefix = nil;
0
+    if (gensymCount > 0) {
0
+        gensymPrefix = [NSString stringWithFormat:@"g%ld", [NuMath random]];
0
+    }
0
+
0
+    id bodyToEvaluate = (gensymCount == 0)
0
+        ? (id)body : [self body:body withGensymPrefix:gensymPrefix symbolTable:symbolTable];
0
 
0
     // uncomment this to get the old (no gensym) behavior.
0
     //bodyToEvaluate = body;
0
@@ -203,6 +209,21 @@ extern id Nu__null;
0
     else {
0
         [calling_context setPossiblyNullObject:old_margs forKey:[symbolTable symbolWithCString:"margs"]];
0
     }
0
+    #if 0
0
+    // I would like to remove gensym values and symbols at the end of a macro's execution,
0
+    // but there is a problem with this: the gensym assignments could be used in a closure,
0
+    // and deleting them would cause that to break. See the testIvarAccessorMacro unit
0
+    // test for an example of this. So for now, the code below is disabled.
0
+    //
0
+    // remove the gensyms from the context; this also releases their assigned values
0
+    NSArray *gensymArray = [gensyms allObjects];
0
+    for (int i = 0; i < gensymCount; i++) {
0
+        NuSymbol *gensymBase = [gensymArray objectAtIndex:i];
0
+        NuSymbol *gensymSymbol = [symbolTable symbolWithString:[NSString stringWithFormat:@"%@%@", gensymPrefix, [gensymBase stringValue]]];
0
+        [calling_context removeObjectForKey:gensymSymbol];
0
+        [symbolTable removeSymbol:gensymSymbol];
0
+    }
0
+    #endif
0
     // NSLog(@"result is %@", value);
0
     return value;
0
 }

0
@@ -23,12 +23,13 @@ limitations under the License.
0
 #import <Foundation/Foundation.h>
0
 #import "nuinternals.h"
0
 
0
+@class NuSymbol;
0
 
0
 /*!
0
-	@class NuSymbolTable
0
-	@abstract The Nu symbol table class.
0
-	@discussion Instances of NuSymbolTable manage collections of NuSymbol objects.
0
-	By default, one NuSymbolTable object is shared by all NuParser objects and execution contexts in a process.
0
+    @class NuSymbolTable
0
+    @abstract The Nu symbol table class.
0
+    @discussion Instances of NuSymbolTable manage collections of NuSymbol objects.
0
+    By default, one NuSymbolTable object is shared by all NuParser objects and execution contexts in a process.
0
  */
0
 @interface NuSymbolTable : NSObject
0
 {
0
@@ -47,27 +48,29 @@ limitations under the License.
0
 - (id) lookup:(const char *) string;
0
 /*! Get an array containing all of the symbols in a symbol table. */
0
 - (NSArray *) all;
0
+/*! Remove a symbol from the symbol table */
0
+- (void) removeSymbol:(NuSymbol *) symbol;
0
 @end
0
 
0
 /*!
0
-	@class NuSymbol
0
-	@abstract The Nu symbol class.
0
-	@discussion Instances of NuSymbol are used to uniquely represent strings in parsed Nu expressions.
0
-	NuSymbol objects are used as keys in local evaluation contexts (typically of type NSMutableDictionary)
0
-	and each NuSymbol may also have a global value bound to it.  
0
-	Symbols ending in a colon (':') are considered "labels" which evaluate to themselves without error, 
0
-	and when a label is found at the head of the list,
0
-	the list is considered to be a special type of list called a property list.  
0
-	Each member of a property list is evaluated and the resulting list is returned with no further evaluation.
0
+    @class NuSymbol
0
+    @abstract The Nu symbol class.
0
+    @discussion Instances of NuSymbol are used to uniquely represent strings in parsed Nu expressions.
0
+    NuSymbol objects are used as keys in local evaluation contexts (typically of type NSMutableDictionary)
0
+    and each NuSymbol may also have a global value bound to it.
0
+    Symbols ending in a colon (':') are considered "labels" which evaluate to themselves without error,
0
+    and when a label is found at the head of the list,
0
+    the list is considered to be a special type of list called a property list.
0
+    Each member of a property list is evaluated and the resulting list is returned with no further evaluation.
0
  */
0
 @interface NuSymbol : NSObject <NSCoding>
0
 {
0
     NuSymbolTable *table;
0
     id value;
0
-    @public // only for use by the symbol table
0
+    @public                                       // only for use by the symbol table
0
     char *string;
0
     bool isLabel;
0
-	bool isGensym;	// in macro evaluation, symbol is replaced with an automatically-generated unique symbol.
0
+    bool isGensym;                                // in macro evaluation, symbol is replaced with an automatically-generated unique symbol.
0
 }
0
 
0
 /*! Get the global value of a symbol. */

0
@@ -100,6 +100,13 @@ static int add_to_array(st_data_t k, st_data_t v, st_data_t d)
0
     return array;
0
 }
0
 
0
+- (void) removeSymbol:(NuSymbol *) symbol
0
+{
0
+    //NSLog(@"removing symbol %@ from table", [symbol stringValue]);
0
+    st_delete(symbol_table, (st_data_t *) &(symbol->string), 0);
0
+    [symbol release]; // on behalf of the table
0
+}
0
+
0
 @end
0
 
0
 @implementation NuSymbol