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Diffstat (limited to 'upstream/mageia-cauldron/man3pm/Tie::Memoize.3pm')
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diff --git a/upstream/mageia-cauldron/man3pm/Tie::Memoize.3pm b/upstream/mageia-cauldron/man3pm/Tie::Memoize.3pm new file mode 100644 index 00000000..af2128e9 --- /dev/null +++ b/upstream/mageia-cauldron/man3pm/Tie::Memoize.3pm @@ -0,0 +1,135 @@ +.\" -*- mode: troff; coding: utf-8 -*- +.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43) +.\" +.\" 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 +.. +.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. +.ie n \{\ +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. 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 >0, 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 +.\" ======================================================================== +.\" +.IX Title "Tie::Memoize 3pm" +.TH Tie::Memoize 3pm 2023-11-28 "perl v5.38.2" "Perl Programmers Reference Guide" +.\" 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 +Tie::Memoize \- add data to hash when needed +.SH SYNOPSIS +.IX Header "SYNOPSIS" +.Vb 5 +\& require Tie::Memoize; +\& tie %hash, \*(AqTie::Memoize\*(Aq, +\& \e&fetch, # The rest is optional +\& $DATA, \e&exists, +\& {%ini_value}, {%ini_existence}; +.Ve +.SH DESCRIPTION +.IX Header "DESCRIPTION" +This package allows a tied hash to autoload its values on the first access, +and to use the cached value on the following accesses. +.PP +Only read-accesses (via fetching the value or \f(CW\*(C`exists\*(C'\fR) result in calls to +the functions; the modify-accesses are performed as on a normal hash. +.PP +The required arguments during \f(CW\*(C`tie\*(C'\fR are the hash, the package, and +the reference to the \f(CW\*(C`FETCH\*(C'\fRing function. The optional arguments are +an arbitrary scalar \f(CW$data\fR, the reference to the \f(CW\*(C`EXISTS\*(C'\fR function, +and initial values of the hash and of the existence cache. +.PP +Both the \f(CW\*(C`FETCH\*(C'\fRing function and the \f(CW\*(C`EXISTS\*(C'\fR functions have the +same signature: the arguments are \f(CW\*(C`$key, $data\*(C'\fR; \f(CW$data\fR is the same +value as given as argument during \fBtie()\fRing. Both functions should +return an empty list if the value does not exist. If \f(CW\*(C`EXISTS\*(C'\fR +function is different from the \f(CW\*(C`FETCH\*(C'\fRing function, it should return +a TRUE value on success. The \f(CW\*(C`FETCH\*(C'\fRing function should return the +intended value if the key is valid. +.SH "Inheriting from \fBTie::Memoize\fP" +.IX Header "Inheriting from Tie::Memoize" +The structure of the \fBtied()\fR data is an array reference with elements +.PP +.Vb 5 +\& 0: cache of known values +\& 1: cache of known existence of keys +\& 2: FETCH function +\& 3: EXISTS function +\& 4: $data +.Ve +.PP +The rest is for internal usage of this package. In particular, if +TIEHASH is overwritten, it should call SUPER::TIEHASH. +.SH EXAMPLE +.IX Header "EXAMPLE" +.Vb 6 +\& sub slurp { +\& my ($key, $dir) = shift; +\& open my $h, \*(Aq<\*(Aq, "$dir/$key" or return; +\& local $/; <$h> # slurp it all +\& } +\& sub exists { my ($key, $dir) = shift; return \-f "$dir/$key" } +\& +\& tie %hash, \*(AqTie::Memoize\*(Aq, \e&slurp, $directory, \e&exists, +\& { fake_file1 => $content1, fake_file2 => $content2 }, +\& { pretend_does_not_exists => 0, known_to_exist => 1 }; +.Ve +.PP +This example treats the slightly modified contents of \f(CW$directory\fR as a +hash. The modifications are that the keys \fIfake_file1\fR and +\&\fIfake_file2\fR fetch values \f(CW$content1\fR and \f(CW$content2\fR, and +\&\fIpretend_does_not_exists\fR will never be accessed. Additionally, the +existence of \fIknown_to_exist\fR is never checked (so if it does not +exists when its content is needed, the user of \f(CW%hash\fR may be confused). +.SH BUGS +.IX Header "BUGS" +FIRSTKEY and NEXTKEY methods go through the keys which were already read, +not all the possible keys of the hash. +.SH AUTHOR +.IX Header "AUTHOR" +Ilya Zakharevich <mailto:perl\-module\-hash\-memoize@ilyaz.org>. |