update

added error to warn about using bytecode export and variable factories. I did not enable the error.  It is not necessarily a problem just tricky to manage.

include/muParserBytecode.h

@@ -151,10 +151,10 @@ namespace mu
 				return &m_vRPN[0];
 		}
 
-		void StoreEnvironment(string_type a_expr, stringbuf_type const& a_strBuf)
+		void StoreEnvironment(string_type expr, stringbuf_type const& strBuf)
 		{
-			m_stringBuffer = a_strBuf;
-			m_expr = a_expr;
+			m_stringBuffer = strBuf;
+			m_expr = expr;
 		}
 
 		std::tuple<string_type, stringbuf_type> RestoreEnvironment() const

include/muParserDef.h

@@ -276,7 +276,9 @@ namespace mu
 		ecINVALID_CHARACTERS_FOUND = 38,///< The expression or identifier contains invalid non printable characters
 
 		// internal errors
-		ecINTERNAL_ERROR = 39,    ///< Internal error of any kind.
+		ecINTERNAL_ERROR = 39,			///< Internal error of any kind.
+
+		ecBYTECODE_IMPORT_EXPORT_DISABLED = 40,	///< Bytecode cannot be exported.
 
 		// The last two are special entries 
 		ecCOUNT,                      ///< This is no error code, It just stores just the total number of error codes

include/muParserTokenReader.h

@@ -67,6 +67,15 @@ namespace mu
 		void SetFormula(const string_type& a_strFormula);
 		void SetArgSep(char_type cArgSep);
 
+		/** \brief Check whether a variable factory is installed. 
+		 
+			Variable factories automatically create new variables when a unknown variable is found in an expression.
+		*/
+		bool HasVarCreator() const
+		{
+			return m_pFactory != nullptr;
+		}
+
 		int GetPos() const;
 		const string_type& GetExpr() const;
 		varmap_type& GetUsedVar();

samples/example1/example1.cpp

@@ -39,6 +39,7 @@
 
 #include "muParserTest.h"
 #include "muParser.h"
+#include "muParserBytecode.h"
 
 using namespace std;
 using namespace mu;

src/muParserBase.cpp

@@ -270,13 +270,23 @@ namespace mu
 	*/
 	const ParserByteCode& ParserBase::GetByteCode() const
 	{
+		// If a variable factory is defined the bytecode may contain references to implicitely 
+		// created variables. 
+//		if (m_pTokenReader->HasVarCreator())
+//			Error(ecBYTECODE_IMPORT_EXPORT_DISABLED);
+
 		return m_vRPN;
 	}
 
 
 	/** \brief Restore a previously saved bytecode. */
 	void ParserBase::SetByteCode(const ParserByteCode& a_ByteCode)
 	{
+		// If a variable factory is defined the bytecode may contain references to dynamically
+		// created variables. 
+//		if (m_pTokenReader->HasVarCreator())
+//			Error(ecBYTECODE_IMPORT_EXPORT_DISABLED);
+
 		m_vRPN = a_ByteCode;
 
 		// restore expression environment