# UNITY_BUILD_FILENAME_PREFIX

Added in version 4.2.

By default, the unity file generated when `UNITY_BUILD` is enabled is of the form `unity_<index>_<suffix>`, where `<suffix>` is language-specific.

If several targets are using unity builds, the build output may give no indication which target a unity file belongs to. This property allows customizing the prefix of the generated unity file name. If unset, the default prefix `unity_` is used.

Example usage:

    add_library(example_library
                source1.cxx
                source2.cxx
                source3.cxx)

    set_target_properties(example_library PROPERTIES
                          UNITY_BUILD True
                          UNITY_BUILD_FILENAME_PREFIX "example_")