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lib/AppConfig.pm  view on Meta::CPAN

And also, through delegation to AppConfig::State:

    define()
    get()
    set()
    varlist()

If you define a variable with one of the above names, you will not be able
to access it directly as an object method.  i.e.

    $config->file();

This will call the file() method, instead of returning the value of the 
'file' variable.  You can work around this by explicitly calling get() and 
set() on a variable whose name conflicts:

    $config->get('file');

or by defining a "safe" alias by which the variable can be accessed:

    $config->define("file", { ALIAS => "fileopt" });
or
    $config->define("file|fileopt");

    ...
    $config->fileopt();

Without parameters, the current value of the variable is returned.  If
a parameter is specified, the variable is set to that value and the 
result of the set() operation is returned.

    $config->age(29);        # sets 'age' to 29, returns 1 (ok)
    print $config->age();    # prints "29"

The varlist() method can be used to extract a number of variables into
a hash array.  The first parameter should be a regular expression 
used for matching against the variable names. 

    my %vars = $config->varlist("^file");   # all "file*" variables

A second parameter may be specified (any true value) to indicate that 
the part of the variable name matching the regex should be removed 
when copied to the target hash.

    $config->file_name("/tmp/file");
    $config->file_path("/foo:/bar:/baz");

    my %vars = $config->varlist("^file_", 1);

    # %vars:
    #    name => /tmp/file
    #    path => "/foo:/bar:/baz"


=head2 READING CONFIGURATION FILES

The AppConfig module provides a streamlined interface for reading 
configuration files with the AppConfig::File module.  The file() method
automatically loads the AppConfig::File module and creates an object 
to process the configuration file or files.  Variables stored in the 
internal AppConfig::State are automatically updated with values specified 
in the configuration file.  

    $config->file($filename);

Multiple files may be passed to file() and should indicate the file name 
or be a reference to an open file handle or glob.

    $config->file($filename, $filehandle, \*STDIN, ...);

The file may contain blank lines and comments (prefixed by '#') which 
are ignored.  Continutation lines may be marked by ending the line with 
a '\'.

    # this is a comment
    callsign = alpha bravo camel delta echo foxtrot golf hipowls \
               india juliet kilo llama mike november oscar papa  \
               quebec romeo sierra tango umbrella victor whiskey \
               x-ray yankee zebra

Variables that are simple flags and do not expect an argument (ARGCOUNT = 
ARGCOUNT_NONE) can be specified without any value.  They will be set with 
the value 1, with any value explicitly specified (except "0" and "off")
being ignored.  The variable may also be specified with a "no" prefix to 
implicitly set the variable to 0.

    verbose                              # on  (1)
    verbose = 1                          # on  (1)
    verbose = 0                          # off (0)
    verbose off                          # off (0)
    verbose on                           # on  (1)
    verbose mumble                       # on  (1)
    noverbose                            # off (0)

Variables that expect an argument (ARGCOUNT = ARGCOUNT_ONE) will be set to 
whatever follows the variable name, up to the end of the current line 
(including any continuation lines).  An optional equals sign may be inserted 
between the variable and value for clarity.

    room = /home/kitchen     
    room   /home/bedroom

Each subsequent re-definition of the variable value overwrites the previous
value.

    print $config->room();               # prints "/home/bedroom"

Variables may be defined to accept multiple values (ARGCOUNT = ARGCOUNT_LIST).
Each subsequent definition of the variable adds the value to the list of
previously set values for the variable.  

    drink = coffee
    drink = tea

A reference to a list of values is returned when the variable is requested.

    my $beverages = $config->drink();
    print join(", ", @$beverages);      # prints "coffee, tea"

Variables may also be defined as hash lists (ARGCOUNT = ARGCOUNT_HASH).
Each subsequent definition creates a new key and value in the hash array.

lib/AppConfig.pm  view on Meta::CPAN

    alias e="emacs"

A reference to the hash is returned when the variable is requested.

    my $aliases = $config->alias();
    foreach my $k (keys %$aliases) {
        print "$k => $aliases->{ $k }\n";
    }

The '-' prefix can be used to reset a variable to its default value and
the '+' prefix can be used to set it to 1

    -verbose
    +debug

=head2 VARIABLE EXPANSION

Variable values may contain references to other AppConfig variables, 
environment variables and/or users' home directories.  These will be 
expanded depending on the EXPAND value for each variable or the GLOBAL
EXPAND value.

Three different expansion types may be applied:

    bin = ~/bin          # expand '~' to home dir if EXPAND_UID
    tmp = ~abw/tmp       # as above, but home dir for user 'abw'

    perl = $bin/perl     # expand value of 'bin' variable if EXPAND_VAR
    ripl = $(bin)/ripl   # as above with explicit parens

    home = ${HOME}       # expand HOME environment var if EXPAND_ENV

See L<AppConfig::State> for more information on expanding variable values.

The configuration files may have variables arranged in blocks.  A block 
header, consisting of the block name in square brackets, introduces a 
configuration block.  The block name and an underscore are then prefixed 
to the names of all variables subsequently referenced in that block.  The 
block continues until the next block definition or to the end of the current 
file.

    [block1]
    foo = 10             # block1_foo = 10

    [block2]
    foo = 20             # block2_foo = 20

=head2 PARSING COMMAND LINE OPTIONS

There are two methods for processing command line options.  The first, 
args(), is a small and efficient implementation which offers basic 
functionality.  The second, getopt(), offers a more powerful and complete
facility by delegating the task to Johan Vroman's Getopt::Long module.  
The trade-off between args() and getopt() is essentially one of speed/size
against flexibility.  Use as appropriate.  Both implement on-demand loading 
of modules and incur no overhead until used.  

The args() method is used to parse simple command line options.  It
automatically loads the AppConfig::Args module and creates an object 
to process the command line arguments.  Variables stored in the internal
AppConfig::State are automatically updated with values specified in the 
arguments.  

The method should be passed a reference to a list of arguments to parse.
The @ARGV array is used if args() is called without parameters.

    $config->args(\@myargs);
    $config->args();               # uses @ARGV

Arguments are read and shifted from the array until the first is
encountered that is not prefixed by '-' or '--'.  At that point, the
method returns 1 to indicate success, leaving any unprocessed arguments
remaining in the list.

Each argument should be the name or alias of a variable prefixed by 
'-' or '--'.  Arguments that are not prefixed as such (and are not an
additional parameter to a previous argument) will cause a warning to be
raised.  If the PEDANTIC option is set, the method will return 0 
immediately.  With PEDANTIC unset (default), the method will continue
to parse the rest of the arguments, returning 0 when done.

If the variable is a simple flag (ARGCOUNT = ARGCOUNT_NONE)
then it is set to the value 1.  The variable may be prefixed by "no" to
set its value to 0.

    myprog -verbose --debug -notaste     # $config->verbose(1)
                                         # $config->debug(1)
                                         # $config->taste(0)

Variables that expect an additional argument (ARGCOUNT != 0) will be set to 
the value of the argument following it.  

    myprog -f /tmp/myfile                # $config->file('/tmp/file');

Variables that expect multiple values (ARGCOUNT = ARGCOUNT_LIST or
ARGCOUNT_HASH) will have successive values added each time the option
is encountered.

    myprog -file /tmp/foo -file /tmp/bar # $config->file('/tmp/foo')
                                         # $config->file('/tmp/bar')

    # file => [ '/tmp/foo', '/tmp/bar' ]

    myprog -door "jim=Jim Morrison" -door "ray=Ray Manzarek"
                                    # $config->door("jim=Jim Morrison");
                                    # $config->door("ray=Ray Manzarek");

    # door => { 'jim' => 'Jim Morrison', 'ray' => 'Ray Manzarek' }

See L<AppConfig::Args> for further details on parsing command line
arguments.

The getopt() method provides a way to use the power and flexibility of
the Getopt::Long module to parse command line arguments and have the 
internal values of the AppConfig object updates automatically.

The first (non-list reference) parameters may contain a number of 
configuration string to pass to Getopt::Long::Configure.  A reference 
to a list of arguments may additionally be passed or @ARGV is used by 
default.