cdl_component

`cdl_component`
	Chapter 5. CDL Language Specification

Description

A component is a configuration option that can contain additional options and sub-components. The body of a cdl_component can contain the same properties as that of a cdl_option. There is an additional property, script which allows configuration data to be split into multiple files. It is also possible for a component body to include cdl_component, cdl_option and cdl_interface entities that should go below this component in the configuration hierarchy.

cdl_component is implemented as a Tcl command that takes two arguments, a name and a body. The name must be a valid C preprocessor identifier: a sequence of upper or lower case letters, digits or underscores, starting with a non-digit character; identifiers beginning with an underscore should normally be avoided because they may clash with system packages or with identifiers reserved for use by the compiler. Within a single configuration, names must be unique. If a configuration contained two packages which defined the same entity CYGIMP_SOME_OPTION, any references to that entity in a requires property or any other expression would be ambiguous. It is possible for a given name to be used by two different packages if those packages should never be loaded into a single configuration. For example, architectural HAL packages are allowed to re-use certain names because a single configuration cannot target two different architectures. For a recommended naming convention see Section 2.3, “Package Contents and Layout”.

The second argument to cdl_component is a body of properties and other commands, typically surrounded by braces so that the Tcl interpreter treats it as a single argument. This body will be processed by a recursive invocation of the Tcl interpreter, extended with additional commands for the various properties that are allowed inside a cdl_component. The valid commands are:

active_if: Allow additional control over the active state of this component.
calculated: The component's value is not directly user-modifiable, it is calculated using a suitable CDL expression.
cdl_component: Define a sub-component.
cdl_interface: Define an interface which should appear immediately below this component in the configuration hierarchy.
cdl_option: Define a configuration option which should appear immediately below this component in the configuration hierarchy.
compile: List the source files that should be built if this component is active and enabled.
default_value: Provide a default value for this component using a CDL expression.
define: Specify additional #define symbols that should go into the owning package's configuration header file.
define_format: Control how the component's value will appear in the configuration header file.
define_proc: Use a fragment of Tcl code to output additional data to configuration header files.
description: Provide a textual description for this component.
display: Provide a short string describing this component.
doc: The location of on-line documentation for this component.
flavor: Specify the nature of this component.
if_define: Output a common preprocessor construct to a configuration header file.
implements: Enabling this component provides one instance of a more general interface.
legal_values: Impose constraints on the possible values for this component.
make: An additional custom build step associated with this component, resulting in a target that should not go directly into a library.
make_object: An additional custom build step associated with this component, resulting in an object file that should go into a library.
no_define: Suppress the normal generation of a preprocessor #define symbol in a configuration header file.
parent: Control the location of this component in the configuration hierarchy.
requires: List constraints that the configuration should satisfy if this component is active and enabled.
script: Include additional configuration information from another CDL script

Example

cdl_component CYGDBG_USE_ASSERTS {
  display       "Use asserts"
  default_value 1
  description   "
    If this component is enabled, assertions in the code are
    tested at run-time. Assert functions (CYG_ASSERT()) are
    defined in 'include/cyg/infra/cyg_ass.h' within the 'install'
    tree. If the component is disabled, these result in no
    additional object code and no checking of the asserted
    conditions."
  script        assert.cdl
}

Name

Synopsis

Description

Example

See Also


`cdl_option`		`cdl_package`