.\" Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
.    if \nF \{
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "Mixin::ExtraFields::Driver 3pm"
.TH Mixin::ExtraFields::Driver 3pm "2013-10-03" "perl v5.18.1" "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"
Mixin::ExtraFields::Driver \- a backend for extra field storage
.SH "VERSION"
.IX Header "VERSION"
version 0.140001
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
This is really not something you'd use on your own, it's just used by
Mixin::ExtraFields, but if you insist...
.PP
.Vb 1
\&  my $driver = Mixin::ExtraFields::Driver::Phlogiston\->from_args(\e%arg);
\&
\&  $driver\->set($obj, $obj_id, flammable => "very!");
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Mixin::ExtraFields::Driver is a base class for drivers used by
Mixin::ExtraFields \*(-- hence the name.  A driver is expected to store and
retrieve data keyed to an object and a name or key.  It can store this in any
way it likes, and does not need to guarantee persistence across processes.
.SH "SUBCLASSING"
.IX Header "SUBCLASSING"
All drivers must implement the four methods listed below.  The base class has
implementations of these methods which will die noisily (\f(CW\*(C`confess\*(C'\fR\-ing) when
called.
.PP
Almost all methods are passed the same data as their first two arguments:
\&\f(CW$object\fR, the object for which the driver is to find or alter data, and
\&\f(CW$id\fR, that object's unique id.  While this may be slighly redundant, it keeps
the id-finding call in one place.
.SS "from_args"
.IX Subsection "from_args"
.Vb 1
\&  my $driver = Mixin::ExtraFields::Driver::Subclass\->from_args(\e%arg);
.Ve
.PP
This method must return a driver object appropriate to the given args.  It is
not called \f(CW\*(C`new\*(C'\fR because it need not return a new object for each call to it.
Returning identical objects for identical configurations may be safe for some
driver implementations, and it is expressly allowed.
.PP
The arguments passed to this method are those given as the \f(CW\*(C`driver\*(C'\fR option to
the \f(CW\*(C`fields\*(C'\fR import group in Mixin::ExtraFields, less the \f(CW\*(C`class\*(C'\fR option.
.SS "get_all_detailed_extra"
.IX Subsection "get_all_detailed_extra"
.Vb 1
\&  my %extra = $driver\->get_all_detailed_extra($object, $id);
.Ve
.PP
This method must return all available information about all existing extra
fields for the given object.  It must be returned as a list of name/value
pairs.  The values must be references to hashes.  Each hash must have an entry
for the key \f(CW\*(C`value\*(C'\fR giving the value for that name.
.SS "set_extra"
.IX Subsection "set_extra"
.Vb 1
\&  $driver\->set_extra($object, $id, $name, $value);
.Ve
.PP
This method must set the named extra to the given value.
.SS "delete_extra"
.IX Subsection "delete_extra"
.Vb 1
\&  $driver\->delete_extra($object, $id, $name);
.Ve
.PP
This method must delete the named extra, causing it to cease to exist.
.SH "OPTIMIZING"
.IX Header "OPTIMIZING"
The methods below can all be implemented in terms of those above.  If they are
not provided by the subclass, basic implementations exist.  These
implementations may be less efficient than implementations crafted for the
specifics of the storage engine behind the driver, so authors of driver
subclasses should consider implementing these methods.
.SS "get_all_extra"
.IX Subsection "get_all_extra"
.Vb 1
\&  my %extra = $driver\->get_all_extra($object, $id);
.Ve
.PP
This method behaves like \f(CW\*(C`get_all_detailed_extra\*(C'\fR, above, but provides the
entry's value, not a detailed hashref, as the value for each entry.
.SS "get_extra"
.IX Subsection "get_extra"
.SS "get_detailed_extra"
.IX Subsection "get_detailed_extra"
.Vb 1
\&  my $value = $driver\->get_extra($object, $id, $name);
\&
\&  my $hash = $driver\->get_detailed_extra($object, $id, $name);
.Ve
.PP
These methods return a single value requested by name, either as the value
itself or a detailed hashref describing it.
.SS "get_all_extra_names"
.IX Subsection "get_all_extra_names"
.Vb 1
\&  my @names = $driver\->get_all_extra_names($object, $id);
.Ve
.PP
This method returns the names of all existing extras for the given object.
.SS "exists_extra"
.IX Subsection "exists_extra"
.Vb 1
\&  if ($driver\->exists_extra($object, $id, $name)) { ... }
.Ve
.PP
This method returns true if an entry exists for the given name and false
otherwise.
.SS "delete_all_extra"
.IX Subsection "delete_all_extra"
.Vb 1
\&  $driver\->delete_all_extra($object, $id);
.Ve
.PP
This method deletes all extras for the object, as per the \f(CW\*(C`delete_extra\*(C'\fR
method.
.SH "AUTHOR"
.IX Header "AUTHOR"
This code was written by Ricardo \s-1SIGNES. \s0 His code in 2006 was sponsored by
Listbox.
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright (C) 2006, Ricardo \s-1SIGNES. \s0 This code is free software, and is
available under the same terms as perl itself.
.SH "AUTHOR"
.IX Header "AUTHOR"
Ricardo Signes <rjbs@cpan.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2013 by Ricardo Signes.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.