no_define

Name

Property no_define -- Suppress the normal generation of a preprocessor #define symbol in a configuration header file.

Synopsis

cdl_option <name> {
    no_define
    …
}

Description

By default all active and enabled properties result in either one or two #define'd symbols in the package's configuration header file, and this is one of the main ways in which options can affect packages at build-time. It is possible to suppress the default #define's by specifying a no_define property in the body of an option or other CDL entity. This property takes no arguments and should occur only once in a given body.

The no_define property is frequently used in conjunction with one of the other header-file related properties such as define. If one of the other properties is used to export the required information to a configuration header file then often there is little point in exporting the default #define as well —  in fact there could be a name clash. The no_define property can also be useful if the sole purpose of an option is to affect which files get built, and the default #define would never get tested in any source code. However in such cases the default #define is mostly harmless and there is little to be gained by suppressing it.

Example

cdl_component CYG_HAL_STARTUP {
    display       "Startup type"
    flavor        data
    legal_values  { "RAM" "ROM" }
    default_value {"RAM"}
    no_define
    define -file system.h CYG_HAL_STARTUP
    …
}
2017-02-09
Documentation license for this page: Open Publication License