ICU Versioning Design

Options

The options that were discussed :
 

• #undef the troublesome symbols in the compilation unit.

Cons:
• Would not rename the ICU related symbols causing loss of versioning information after the symbols is undefined.
• The clients application may not link since the symbols are not valid entry points in the library.

•  Use namespaces

Pros:
• Do not need to rename class names.


Cons:

• All C++ compilers may not support namespaces, especially OS390, AS400 and AIX
• Does not solve the problem if versioning is included in the class name but will if the namespace includes versioning.
• Current versioning mechanism needs to be changed so that the namespace includes the version information. e.g.:
/************* namespace.h ********************/
#include <iostream.h>
#include <afx.h>

#define ICU ICU_1_9

namespace ICU{
        class Format{
          public:
                static void printString(){
                          ::cout<<"Hello World" <<endl;
                }
        };

}

/************** namespace.cpp****************/
#include "namespace.h"

using namespace ICU;

int main(){

        Format::printString();
        CString str = "adfasdfasdf";
        str.Format("afdsfafd");
        return 0;
}

•  Rename all ICU classes to include prefix ICU, e.g.: Format class will be renamed to ICUFormat

Pros:
• Do not need to depend on namespace support on different compilers.
• Do not need to change the current versioning mechanism


Cons:

• Need to rename all C++ classes
• Test, document and port code on all platforms
• Provide compatibility layer clients using old class names

• Use typedef.

Cons:
• Requires renaming of class names to include the version. e.g.:
        class Format{ ..... } ;

        is renamed to

        class Format_1_9{.......};
        typedef Format_1_9 Format;

Proposed course of action

Check all IBM clients' platforms (OS390, AS400, AIX) and compilers like
GCC, HPUX, CXX, SUN's compilers for namespace support.
 

Support available	Support not available on certain platforms
Create namespace for all c++ classe	Rename all C++ classes
Put c++ rename undef flags if C++	Modify header files and CPP files
Put namespace in the header	Document and change userguide to reflect changes
Conduct tests on compiler support	Compile files with #ifdef

 

Current course of action

After initial investigation on compilers and namespaces it turned out that AIX does not  support namespaces. Since AIX is one of the main IBM platforms,
namespaces solution cannot be used.
 

Rename all C++ classes

Modify header files and CPP files

Document and change userguide to reflect changes

Compile files with #ifdef