| Config::Model::Backend::Any(3pm) | User Contributed Perl Documentation | Config::Model::Backend::Any(3pm) |
Config::Model::Backend::Any - Virtual class for other backends
version 2.152
package Config::Model::Backend::Foo ;
use Mouse ;
extends 'Config::Model::Backend::Any';
# mandatory
sub read {
my $self = shift ;
my %args = @_ ;
# args are:
# root => './my_test', # fake root directory, used for tests
# config_dir => /etc/foo', # absolute path
# file => 'foo.conf', # file name
# file_path => Path::Tiny object for './my_test/etc/foo/foo.conf'
# check => yes|no|skip
return 0 unless $args{file_path}->exists ; # or die, your choice
# read the file line by line
# we assume the file contain lines like 'key=value'
foreach ($args{file_path}->lines_utf8) {
chomp ; # remove trailing \n
s/#.*// ; # remove any comment
next unless /\S/; # skip blank line
# $data is 'foo=bar' which is compatible with load
$self->node->load(steps => $_, check => $args{check} ) ;
}
return 1 ;
}
# mandatory
sub write {
my $self = shift ;
my %args = @_ ;
# args are:
# root => './my_test', # fake root directory, used for tests
# config_dir => /etc/foo', # absolute path
# file => 'foo.conf', # file name
# file_path => Path::Tiny object for './my_test/etc/foo/foo.conf'
# check => yes|no|skip
# read the content of the configuration tree
my @lines;
foreach my $elt ($self->node->children) {
# read the value from element $elt
my $v = $self->node->grab_value($elt) ;
# write value in file
push @lines,qq!$elt="$v"\n! if defined $v ;
}
$args{file_path}->spew_utf8(@lines);
return 1;
}
Some application have configuration files with a syntax which is not supported by existing "Config::Model::Backend::*" classes.
In this case a new backend must be written. "Config::Model::Backend::Any" was created to facilitate this task.
The new backend class must use Mouse and must extends (inherit) "Config::Model::Backend::Any".
As explained in "Backend specification" in Config::Model::BackendMgr, the new backend must be declared as an attribute of a Config::Model::Node specification.
Let's say your new backend is "Config::Model::Backend::Foo". This new backend can be specified with:
rw_config => {
backend => 'Foo' , # can also be 'foo'
config_dir => '/etc/cfg_dir'
file => 'foo.conf', # optional
}
(The backend class name is constructed with "ucfirst($backend_name)")
"rw_config" can also have custom parameters that are passed verbatim to "Config::Model::Backend::Foo" methods:
rw_config => {
backend => 'Foo' , # can also be 'foo'
config_dir => '/etc/cfg_dir'
file => 'foo.conf', # optional
my_param => 'my_value',
}
"Config::Model::Backend::Foo" class must inherit (extend) Config::Model::Backend::Any and is expected to provide the following methods:
%custom_parameters, # e.g. my_param => 'my_value' in the example above
object => $obj, # Config::Model::Node object
root => $root_dir, # fake root directory, used for tests
backend => $backend, # backend name
config_dir => $read_dir, # path below root
file => 'foo.conf', # file name
file_path => $full_name, # Path::Tiny object
check => [yes|no|skip]
The IO::File object is undef if the file cannot be read.
This method must return 1 if the read was successful, 0 otherwise.
Following the "my_param" example above, %custom_parameters contains " ( 'my_param' , 'my_value' ) ", so "read()" is called with "root", "config_dir", "file_path" and "my_param => 'my_value'".
%$custom_parameters, # e.g. my_param => 'my_value' in the example above
object => $obj, # Config::Model::Node object
root => $root_dir, # fake root directory, used for tests
auto_create => $auto_create, # boolean specified in backend declaration
auto_delete => $auto_delete, # boolean specified in backend declaration
backend => $backend, # backend name
config_dir => $write_dir, # override from instance
file => 'foo.conf', # file name
file_path => $full_name, # full file name (root+path+file)
write => 1, # always
check => [ yes|no|skip] ,
backup => [ undef || '' || suffix ] # backup strategy required by user
The IO::File object is undef if the file cannot be written to.
This method must return 1 if the write was successful, 0 otherwise
Using Config::Model::Tester, you can test your model with your backend following the instructions given in Config::Model::Tester.
You can also test your backend with a minimal model (and Config::Model::Tester). In this case, you need to specify a small model to test in a "*-test-conf.pl" file. See the IniFile backend test <https://github.com/dod38fr/config-model/blob/master/t/model_tests.d/backend-ini-test-conf.pl> for an example and its examples files <https://github.com/dod38fr/config-model/tree/master/t/model_tests.d/backend-ini-examples>.
The constructor should be used only by Config::Model::Node.
Parameter:
Whether the backend supports reading and writing annotation (a.k.a comments). Default is 0. Override this method to return 1 if your backend supports annotations.
Read the configuration file. This method must be overridden.
Write the configuration file. This method must be overridden.
Return the node (a Config::Model::Node) holding this backend.
Return the instance (a Config::Model::Instance) holding this configuration.
Parameters: "( string )"
Show a message to STDOUT (unless overridden). Delegated to "show_message" in Config::Model::Instance.
Parameters:
Read the global comments (i.e. the first block of comments until the first blank or non comment line) and store them as root node annotation. Note that the global comment must be separated from the first data line by a blank line.
Example:
$self->read_global_comments( \@lines, ';'); $self->read_global_comments( \@lines, '#;');
Parameters:
This method extracts comments from the passed lines and associate them with actual data found in the file lines. Data is associated with comments preceding or on the same line as the data. Returns a list of [ data, comment ].
Example:
my @lines = (
'# Foo comments',
'foo= 1',
'Baz = 0 # Baz comments'
);
my @res = $self->associates_comments_with_data( \@lines, '#')
# @res is:
# ( [ 'foo= 1', 'Foo comments' ] , [ 'Baz = 0' , 'Baz comments' ] )
Return a string containing global comments using data from configuration root annotation.
Requires one parameter: comment_char (e.g "#" or '//' )
Example:
my $str = $self->write_global_comments('#')
Returns a string containing comments (stored in annotation) and corresponding data. Comments are written before the data. If a data is undef, the comment is written on its own line.
Positional parameters are "( comment_char , data1, comment1, data2, comment2 ...)"
Example:
print $self->write_data_and_comments('#', 'foo', 'foo comment', undef, 'lone comment','bar')
# returns "# foo comment\nfoo\n#lon
Use "undef" as comment char if comments are not supported by the syntax of the configuration file. Comments will then be dropped.
Custom backend are now deprecated and must be replaced with a class inheriting this module.
Please:
Here's an example of such a change <https://github.com/dod38fr/config-model/commit/c3b7007ad386cb2356c5ac1499fe51bdf492b19a>.
Dominique Dumont, (ddumont at cpan dot org)
Config::Model, Config::Model::BackendMgr, Config::Model::Node,
Dominique Dumont
This software is Copyright (c) 2005-2022 by Dominique Dumont.
This is free software, licensed under:
The GNU Lesser General Public License, Version 2.1, February 1999
| 2022-07-28 | perl v5.34.0 |