NAME

       ConfigReader::DirectiveStyle - read configuration file

       Reads a configuration file of directives and values.

CONFIGURATION FILE SYNOPSIS

           # comments start with a #, and blank lines are ignored

           Input     /etc/data_source      # the value follows the directive name
           HomePage  http://www.w3.org/

           # values can be quoted
           Comment   "here is a value with trailing spaces   "

CODE SYNOPSIS

           my $c = new ConfigReader::DirectiveStyle;

           directive $c 'Input', undef, '~/input';  # specify default value,
                                                    #   but no parsing needed
           required  $c 'HomePage', 'new URI::URL'; # create URI::URL object
           ignore    $c 'Comment';                  # Ignore this directive.

           $c->load('my.config');
           open(IN, $c->value("Input"));

           $c->define_accessors();                  # creates Input() and HomePage()
           retrieve(HomePage());

DESCRIPTION

       This class reads a common style of configuration files, where directive names are followed
       by a value.  For each directive you can specify whether it has a default value or is
       required, and a function or method to use to parse the value.  Errors and warnings are
       caught while parsing, and the location where the offending value came from (either from
       the configuration file, or your Perl source for default values) is reported.

       DirectiveStyle is a subclass of ConfigReader::Values.  The methods to define the
       directives in the configuration file are documented there.

       Comments are introduced by the "#" character, and continue until the end of line.  Like in
       Perl, the backslash character "\" may be used in the directive values for the various
       standard sequences:

            \t          tab
            \n          newline
            \r          return
            \f          form feed
            \v          vertical tab, whatever that is
            \b          backspace
            \a          alarm (bell)
            \e          escape
            \033        octal char
            \x1b        hex char

       The value may also be quoted, which lets you include leading or trailing spaces.  The
       quotes are stripped off before the value is returned.

       DirectiveStyle itself only reads the configuration file.  Most of the hard work of
       defining the directives and parsing the values is done in its superclass,
       ConfigReader::Values.  You should be able to easily modify or subclass DirectiveStyle to
       read a different style of configuration file.

PUBLIC METHODS

   "new( [$spec] )"
       This static method creates and returns a new DirectiveStyle object.  For information about
       the optional $spec argument, see DirectiveStyle::new().

   "load($file, [$untaint])"
       Before calling load(), you'll want to define the directives using the methods described in
       ConfigReader::Values.

       Reads a configuration from $file.  The default values for any directives not present in
       the file are assigned.

       Normally configuration values are tainted like any data read from a file.  If the
       configuration file comes from a trusted source, you can untaint all the values by setting
       the optional $untaint argument to a true value (such as 'UNTAINT').

SUBCLASSABLE METHODS

       You can stop reading here if you just want to use DirectiveStyle.  The following methods
       could be overridden in a subclass to provide additional or alternate functionality.

   "parse_line($line, $whence, $untaint)"
       Parses $line.  $whence is a string describing the source of the line.  Returns a two-
       element array of the directive and the value string, or the empty array () if the line is
       blank or only contains a comment.

   "parse_value_string($str, $whence)"
       Interprets quotes, backslashes, and comments in the value part.  (Note that after the
       value string is returned, it will still get passed to the directive's parsing function of
       method if one is defined).