Native Symbian OS EXEs and LIBs vs. OE EXEs and LIBs

The conventional way of defining the entry point for a Symbian OS executable is by including "E32Main" in the application source. Since Symbian OS v9.3, you can define the entry point for an executable by including "main" instead of "E32Main". With this approach, developers may easily port their C/C++ code to Symbian OS platforms with less changes to the original source.

Symbian OS v9.3 and later releases provide an Open Environment (OE) to develop EXEs with the "main" entry point. The OE executables and libraries are identified by their targettype, which can either be STDEXE, STDDLL or STDLIB. An OE EXE may choose to have a wide character entry point using the MMP keyword, wcharentrypoint.

Here is a list of important differences between native Symbian OS executables and OE executables:

• Native Symbian OS EXEs use "E32Main" entry point, whereas OE EXEs use "main" entry point.

• The UIDs used to identify native Symbian OS EXEs and DLLs are different when compared to OE EXEs and DLLs.

• In a native Symbian OS executable, the functions and data symbols with extern linkage are exported only if IMPORT_C/EXPORT_C declarations are found in the header or source files. In a OE executable, all functions and data symbols with extern linkage are exported by default without IMPORT_C/EXPORT_C declarations in the header or source files.

• The libraries required by a native Symbian OS executable/library have to be listed explicitly in the MMP file, whereas for an OE executable/library they are included by default.

• The native Symbian OS EXEs and DLLs does not have symbol lookup, whereas OE EXEs and DLLs support symbol lookup using dlsym.

• A native Symbian OS EXE, DLL or LIB must include the path to standard APIs in the mmp file. For an OE EXE, DLL or LIB the build system includes ${EPOCROOT}epoc32/include/stdapis as the default path for header files.

The build system has been modified to support compilation of C++ source files with extensions “.cc”, “.cxx” and “.c++”. This change is applicable to both OE and native Symbian OS executables and libraries. That is, from Symbian OS v9.3 onwards a native Symbian OS or an OE executable/library can be built using C++ source files with extensions “.cc”, “.cxx” and “.c++”.