Compilation and Linking Details

Once you've written your code, you need to compile it and link it into IDL before it can be run. Information on how to do this is available in the various subdirectories of the external subdirectory of the IDL distribution. References to files that are useful in specific situations are contained in this book.

The IDL MAKE_DLL procedure, documented in the IDL Reference Manual, provides a portable high level mechanism for building sharable libraries from code written in the C programming language.

The IDL !MAKE_DLL system variable is used by the MAKE_DLL procedure to construct C compiler and linker commands appropriate for the target platform. If you do not use MAKE_DLL to compile and link your code, you may find the value of !MAKE_DLL.CC and !MAKE_DLL.LD helpful in determining which options to specify to your compiler and linker, in conjunction with your system and compiler documentation. For the C language, the options in !MAKE_DLL should be very close to what you need. For other languages, the !MAKE_DLL options should still be helpful in determining which options to use, as on most systems, all the language compilers accept similar options.

The UNIX IDL distribution has a bin subdirectory that contains platform specific directories that in turn hold the actual IDL binary and related files. Included with these files is a Makefile that shows how to build IDL from the shareable libraries present in the directory. The link line in this makefile should be used as a starting point when linking your code with Callable IDL—simply omit main.o and include your own object files, containing your own main program.

A more detailed description of the issues involved in compiling and linking your code can be found in this book under Compiling Programs That Call IDL.