cdl_component

Name

Command cdl_component -- Define a component, a collection of configuration options

Synopsis

cdl_component <name> {
    …
}

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 the Section called Package Contents and Layout in Chapter 2.

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
}

See Also

Command cdl_option, command cdl_package, command cdl_interface.

2017-02-09
Documentation license for this page: Open Publication License