Perl::Critic::Policy(3User Contributed Perl DocumentatiPerl::Critic::Policy(3)NAMEPerl::Critic::Policy - Base class for all Policy modules.
DESCRIPTIONPerl::Critic::Policy is the abstract base class for all Policy objects.
If you're developing your own Policies, your job is to implement and
override its methods in a subclass. To work with the Perl::Critic
engine, your implementation must behave as described below. For a
detailed explanation on how to make new Policy modules, please see the
Perl::Critic::DEVELOPER document included in this distribution.
INTERFACE SUPPORT
This is considered to be a public class. Any changes to its interface
will go through a deprecation cycle.
METHODS
"new( ... )"
Don't call this. As a Policy author, do not implement this. Use
the "initialize_if_enabled()" method for your Policy setup. See
the developer documentation for more.
"initialize_if_enabled( $config )"
This receives an instance of Perl::Critic::PolicyConfig as a
parameter, and is only invoked if this Policy is enabled by the
user. Thus, this is the preferred place for subclasses to do any
initialization.
Implementations of this method should return a boolean value
indicating whether the Policy should continue to be enabled. For
most subclasses, this will always be $TRUE. Policies that depend
upon external modules or other system facilities that may or may
not be available should test for the availability of these
dependencies and return $FALSE if they are not.
"prepare_to_scan_document( $document )"
The parameter is about to be scanned by this Policy. Whatever this
Policy wants to do in terms of preparation should happen here.
Returns a boolean value indicating whether the document should be
scanned at all; if this is a false value, this Policy won't be
applied to the document. By default, does nothing but return
$TRUE.
" violates( $element, $document ) "
Given a PPI::Element and a PPI::Document, returns one or more
Perl::Critic::Violation objects if the $element violates this
Policy. If there are no violations, then it returns an empty list.
If the Policy encounters an exception, then it should "croak" with
an error message and let the caller decide how to handle it.
"violates()" is an abstract method and it will abort if you attempt
to invoke it directly. It is the heart of all Policy modules, and
your subclass must override this method.
" violation( $description, $explanation, $element ) "
Returns a reference to a new "Perl::Critic::Violation" object. The
arguments are a description of the violation (as string), an
explanation for the policy (as string) or a series of page numbers
in PBP (as an ARRAY ref), a reference to the PPI element that
caused the violation.
These are the same as the constructor to Perl::Critic::Violation,
but without the severity. The Policy itself knows the severity.
" new_parameter_value_exception( $option_name, $option_value, $source,
$message_suffix ) "
Create a
Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue
for this Policy.
" throw_parameter_value_exception( $option_name, $option_value,
$source, $message_suffix ) "
Create and throw a
Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue.
Useful in parameter parser implementations.
" get_long_name() "
Return the full package name of this policy.
" get_short_name() "
Return the name of this policy without the "Perl::Critic::Policy::"
prefix.
" is_enabled() "
Answer whether this policy is really active or not. Returns a true
value if it is, a false, yet defined, value if it isn't, and an
undefined value if it hasn't yet been decided whether it will be.
" applies_to() "
Returns a list of the names of PPI classes that this Policy cares
about. By default, the result is "PPI::Element". Overriding this
method in Policy subclasses should lead to significant performance
increases.
" default_maximum_violations_per_document() "
Returns the default maximum number of violations for this policy to
report per document. By default, this not defined, but subclasses
may override this.
" get_maximum_violations_per_document() "
Returns the maximum number of violations this policy will report
for a single document. If this is not defined, then there is no
limit. If "set_maximum_violations_per_document()" has not been
invoked, then "default_maximum_violations_per_document()" is
returned.
" set_maximum_violations_per_document() "
Specify the maximum violations that this policy should report for a
document.
" default_severity() "
Returns the default severity for violating this Policy. See the
$SEVERITY constants in Perl::Critic::Utils for an enumeration of
possible severity values. By default, this method returns
$SEVERITY_LOWEST. Authors of Perl::Critic::Policy subclasses
should override this method to return a value that they feel is
appropriate for their Policy. In general, Polices that are widely
accepted or tend to prevent bugs should have a higher severity than
those that are more subjective or cosmetic in nature.
" get_severity() "
Returns the severity of violating this Policy. If the severity has
not been explicitly defined by calling "set_severity", then the
"default_severity" is returned. See the $SEVERITY constants in
Perl::Critic::Utils for an enumeration of possible severity values.
" set_severity( $N ) "
Sets the severity for violating this Policy. Clients of
Perl::Critic::Policy objects can call this method to assign a
different severity to the Policy if they don't agree with the
"default_severity". See the $SEVERITY constants in
Perl::Critic::Utils for an enumeration of possible values.
" default_themes() "
Returns a sorted list of the default themes associated with this
Policy. The default method returns an empty list. Policy authors
should override this method to return a list of themes that are
appropriate for their policy.
" get_themes() "
Returns a sorted list of the themes associated with this Policy.
If you haven't added themes or set the themes explicitly, this
method just returns the default themes.
" set_themes( @THEME_LIST ) "
Sets the themes associated with this Policy. Any existing themes
are overwritten. Duplicate themes will be removed.
" add_themes( @THEME_LIST ) "
Appends additional themes to this Policy. Any existing themes are
preserved. Duplicate themes will be removed.
" get_abstract() "
Retrieve the abstract for this policy (the part of the NAME section
of the POD after the module name), if it is available.
" get_raw_abstract() "
Retrieve the abstract for this policy (the part of the NAME section
of the POD after the module name), if it is available, in the
unparsed form.
" parameter_metadata_available() "
Returns whether information about the parameters is available.
" get_parameters() "
Returns a reference to an array containing instances of
Perl::Critic::PolicyParameter.
Note that this will return an empty list if the parameters for this
policy are unknown. In order to differentiate between this
circumstance and the one where this policy does not take any
parameters, it is necessary to call
"parameter_metadata_available()".
"set_format( $format )"
Class method. Sets the format for all Policy objects when they are
evaluated in string context. The default is "%p\n". See
"OVERLOADS" for formatting options.
"get_format()"
Class method. Returns the current format for all Policy objects
when they are evaluated in string context.
"to_string()"
Returns a string representation of the policy. The content of the
string depends on the current value returned by "get_format()".
See "OVERLOADS" for the details.
"is_safe()"
Answer whether this Policy can be used to analyze untrusted code,
i.e. the Policy doesn't have any potential side effects.
This method returns a true value by default.
An "unsafe" policy might attempt to compile the code, which, if you
have "BEGIN" or "CHECK" blocks that affect files or connect to
databases, is not a safe thing to do. If you are writing a such a
Policy, then you should override this method to return false.
By default Perl::Critic will not run unsafe policies.
DOCUMENTATION
When your Policy module first "use"s Perl::Critic::Violation, it will
try and extract the DESCRIPTION section of your Policy module's POD.
This information is displayed by Perl::Critic if the verbosity level is
set accordingly. Therefore, please include a DESCRIPTION section in
the POD for any Policy modules that you author. Thanks.
OVERLOADS
Perl::Critic::Violation overloads the "" operator to produce neat
little messages when evaluated in string context.
Formats are a combination of literal and escape characters similar to
the way "sprintf" works. If you want to know the specific formatting
capabilities, look at String::Format. Valid escape characters are:
%P Name of the Policy module.
%p Name of the Policy without the "Perl::Critic::Policy::" prefix.
%a The policy abstract.
%O List of supported policy parameters. Takes an option of a format
string for "to_formatted_string" in Perl::Critic::PolicyParameter.
For example, this can be used like "%{%n - %d\n}O" to get a list of
parameter names followed by their descriptions.
%U A message stating that the parameters for the policy are unknown if
"parameter_metadata_available()" returns false. Takes an option of
what the message should be, which defaults to "Cannot
programmatically discover what parameters this policy takes.". The
value of this option is interpolated in order to expand the
standard escape sequences ("\n", "\t", etc.).
%S The default severity level of the policy.
%s The current severity level of the policy.
%T The default themes for the policy.
%t The current themes for the policy.
%V The default maximum number of violations per document of the
policy.
%v The current maximum number of violations per document of the
policy.
AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights
reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself. The full text of this license can
be found in the LICENSE file included with this module.
perl v5.14.1 2011-07-22 Perl::Critic::Policy(3)
