The "config_data" tool provides a command-line interface to the
configuration of Perl modules. By ``configuration'', we mean something
akin to ``user preferences'' or ``local settings''. This is a
formalization and abstraction of the systems that people like Andreas
Koenig ("CPAN::Config"), Jon Swartz ("HTML::Mason::Config"), Andy
Wardley ("Template::Config"), and Larry Wall (perl's own Config.pm)
have developed independently.
The configuration system emplyed here was developed in the context of
"Module::Build". Under this system, configuration information for a
module "Foo", for example, is stored in a module called
"Foo::ConfigData") (I would have called it "Foo::Config", but that
was taken by all those other systems mentioned in the previous
paragraph...). These "...::ConfigData" modules contain the
configuration data, as well as publically accessible methods for
querying and setting (yes, actually re-writing) the configuration
data. The "config_data" script (whose docs you are currently
reading) is merely a front-end for those methods. If you wish, you
may create alternate front-ends.
The two types of data that may be stored are called "config" values
and "feature" values. A "config" value may be any perl scalar,
including references to complex data structures. It must, however, be
serializable using "Data::Dumper". A "feature" is a boolean (1 or
0) value.
USAGE
This script functions as a basic getter/setter wrapper around the
configuration of a single module. On the command line, specify which
module's configuration you're interested in, and pass options to get
or set "config" or "feature" values. The following options are
supported:
module
Specifies the name of the module to configure (required).
feature
When passed the name of a "feature", shows its value. The value will
be 1 if the feature is enabled, 0 if the feature is not enabled, or
empty if the feature is unknown. When no feature name is supplied,
the names and values of all known features will be shown.
config
When passed the name of a "config" entry, shows its value. The value
will be displayed using "Data::Dumper" (or similar) as perl code.
When no config name is supplied, the names and values of all known
config entries will be shown.
set_feature
Sets the given "feature" to the given boolean value. Specify the value
as either 1 or 0.
set_config
Sets the given "config" entry to the given value.
eval
If the "--eval" option is used, the values in "set_config" will be
evaluated as perl code before being stored. This allows moderately
complicated data structures to be stored. For really complicated
structures, you probably shouldn't use this command-line interface,
just use the Perl API instead.
help
Prints a help message, including a few examples, and exits.