I have a program that currently outputs Excel via SpreadsheetML files. I build these using streams. This is very space inefficient for Excel; the files can be 5 to 6 times as large as other Excel binary formats.
I would like to output a binary excel format such as .xls or .xlsx, but I don't want to have the installation of the program depend on Office. Some users might have it installed, some might not. How can I handle this gracefully? Is it possible to not have an assembly as a dependency but based on the user enabling binary output still use the assembly?