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.\" ========================================================================
.\"
.IX Title "Declare::Constraints::Simple::Library::Base 3pm"
.TH Declare::Constraints::Simple::Library::Base 3pm "2021-01-09" "perl v5.32.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Declare::Constraints::Simple::Library::Base \- Library Base Class
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&  package My::Constraint::Library;
\&  use warnings;
\&  use strict;
\&
\&  # this installs the base class and helper functions
\&  use Declare::Constraints::Simple\-Library;
\&
\&  # we can also automagically provide other libraries
\&  # to the importer
\&  use base \*(AqDeclare::Constraints::Simple::Library::Numericals\*(Aq;
\&
\&  # with this we define a constraint to check a value
\&  # against a serial number regular expression
\&  constraint \*(AqSomeSerial\*(Aq,
\&    sub {
\&      return sub {
\&        return _true if $_[0] =~ /\ed{3}\-\ed{3}\-\ed{4}/;
\&        return _false(\*(AqNot in SomeSerial format\*(Aq);
\&      };
\&    };
\& 
\&  1;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This base class contains the common library functionalities. This 
includes helper functions and install mechanisms.
.SH "METHODS"
.IX Header "METHODS"
.SS "install_into($target)"
.IX Subsection "install_into($target)"
Installs the base classes and helper functions into the \f(CW$target\fR
namespace. The \f(CW%CONSTRAINT_GENERATORS\fR package variable of that class
will be used as storage for it's constraints.
.SS "\fBfetch_constraint_declarations()\fP"
.IX Subsection "fetch_constraint_declarations()"
Class method. Returns all constraints registered to the class.
.SS "fetch_constraint_generator($name)"
.IX Subsection "fetch_constraint_generator($name)"
Class method. Returns the constraint generator code reference registered
under \f(CW$name\fR. The call will raise a \f(CW\*(C`croak\*(C'\fR if the generator could not
be found.
.ie n .SS "prepare_generator($constraint_name, $generator)"
.el .SS "prepare_generator($constraint_name, \f(CW$generator\fP)"
.IX Subsection "prepare_generator($constraint_name, $generator)"
Class method. This wraps the \f(CW$generator\fR in a closure that provides
stack and failure-collapsing decisions.
.ie n .SS "add_constraint_generator($name, $code)"
.el .SS "add_constraint_generator($name, \f(CW$code\fP)"
.IX Subsection "add_constraint_generator($name, $code)"
Class method. The actual registration method, used by \f(CW\*(C`constraint\*(C'\fR.
.SH "HELPER FUNCTIONS"
.IX Header "HELPER FUNCTIONS"
Note that some of the helper functions are prefixed with \f(CW\*(C`_\*(C'\fR. Although
this means they are internal functions, it is ok to call them, as they
have a fixed \s-1API.\s0 They are not distribution internal, but library 
internal, and only intended to be used from inside constraints.
.ie n .SS "constraint($name, $code)"
.el .SS "constraint($name, \f(CW$code\fP)"
.IX Subsection "constraint($name, $code)"
.Vb 1
\&  constraint \*(AqFoo\*(Aq, sub { ... };
.Ve
.PP
This registers a new constraint in the calling library. Note that
constraints \fBhave to\fR return result objects. To do this, you can use the
helper functions \*(L"_result($bool, \f(CW$msg\fR\*(R", \fB_true()\fR and _false($msg).
.ie n .SS "_result($bool, $msg)"
.el .SS "_result($bool, \f(CW$msg\fP)"
.IX Subsection "_result($bool, $msg)"
Returns a new result object. It's validity flag will depend on the
\&\f(CW$bool\fR argument. The \f(CW$msg\fR argument is the error message to use on
failure.
.SS "_false($msg)"
.IX Subsection "_false($msg)"
Returns a non-valid result object, with it's message set to \f(CW$msg\fR.
.SS "\fB_true()\fP"
.IX Subsection "_true()"
Returns a valid result object.
.SS "_info($info)"
.IX Subsection "_info($info)"
Sets the current failure info to use in the stack info part.
.SS "_apply_checks($value, \e@constraints, [$info])"
.IX Subsection "_apply_checks($value, @constraints, [$info])"
This applies all constraints in the \f(CW\*(C`\e@constraints\*(C'\fR array reference to
the passed \f(CW$value\fR. You can optionally specify an \f(CW$info\fR string to be
used in the stack of the newly created non-valid results.
.SS "_listify($value)"
.IX Subsection "_listify($value)"
Puts \f(CW$value\fR into an array reference and returns it, if it isn't 
already one.
.ie n .SS "_with_message($msg, $closure, @args)"
.el .SS "_with_message($msg, \f(CW$closure\fP, \f(CW@args\fP)"
.IX Subsection "_with_message($msg, $closure, @args)"
This is the internal version of the general \f(CW\*(C`Message\*(C'\fR constraint. It 
sets the current overridden message to \f(CW$msg\fR and executes the
\&\f(CW$closure\fR with \f(CW@args\fR as arguments.
.ie n .SS "_with_scope($scope_name, $constraint, @args)"
.el .SS "_with_scope($scope_name, \f(CW$constraint\fP, \f(CW@args\fP)"
.IX Subsection "_with_scope($scope_name, $constraint, @args)"
Applies the \f(CW$constraint\fR to \f(CW@args\fR in a newly created scope named
by \f(CW$scope_name\fR.
.ie n .SS "_set_result($scope, $name, $result)"
.el .SS "_set_result($scope, \f(CW$name\fP, \f(CW$result\fP)"
.IX Subsection "_set_result($scope, $name, $result)"
Stores the given \f(CW$result\fR unter the name \f(CW$name\fR in \f(CW$scope\fR.
.ie n .SS "_get_result($scope, $name)"
.el .SS "_get_result($scope, \f(CW$name\fP)"
.IX Subsection "_get_result($scope, $name)"
Returns the result named \f(CW$name\fR from \f(CW$scope\fR.
.ie n .SS "_has_result($scope, $name)"
.el .SS "_has_result($scope, \f(CW$name\fP)"
.IX Subsection "_has_result($scope, $name)"
Returns true only if such a result was registered already.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Declare::Constraints::Simple, Declare::Constraints::Simple::Library
.SH "AUTHOR"
.IX Header "AUTHOR"
Robert 'phaylon' Sedlacek \f(CW\*(C`<phaylon@dunkelheit.at>\*(C'\fR
.SH "LICENSE AND COPYRIGHT"
.IX Header "LICENSE AND COPYRIGHT"
This module is free software, you can redistribute it and/or modify it 
under the same terms as perl itself.