13. A computer system for marshaling of a parameter for inter-language invocation of functions between a first language and a second language, the parameter to be marshaled having a type in the first language and another type in the second language, comprising: a storage component containing custom marshaling code for converting parameters of certain types to parameters of other types and for converting the parameters of the other types to parameters of the certain types; a component for receiving custom marshaling code and adding the received code to the storage component; and a marshaling component that when a computer program implemented in the first language invokes a function implemented in the second language, creates an in stub and an out stub; retrieves the custom marshaling code for converting the parameter based on the type of the parameter in the first and second languages and includes the code within the in stub and the out stub, executes the in stub, thereby converting the passed parameter of a first type to a parameter of a second type, invokes the function implemented in the second language passing the parameter converted to the second type, and after invocation of the function, executes the out stub, thereby converting the parameter of the second type to a parameter of the first type.
13. A computer system for marshaling of a parameter for inter-language invocation of functions between a first language and a second language, the parameter to be marshaled having a type in the first language and another type in the second language, comprising: a storage component containing custom marshaling code for converting parameters of certain types to parameters of other types and for converting the parameters of the other types to parameters of the certain types; a component for receiving custom marshaling code and adding the received code to the storage component; and a marshaling component that when a computer program implemented in the first language invokes a function implemented in the second language, creates an in stub and an out stub; retrieves the custom marshaling code for converting the parameter based on the type of the parameter in the first and second languages and includes the code within the in stub and the out stub, executes the in stub, thereby converting the passed parameter of a first type to a parameter of a second type, invokes the function implemented in the second language passing the parameter converted to the second type, and after invocation of the function, executes the out stub, thereby converting the parameter of the second type to a parameter of the first type. 15. The system of claim 13 wherein the first language is the C++ programming language.