filecache(3pm) [osx man page]
FileCache(3pm) Perl Programmers Reference Guide FileCache(3pm) NAME
FileCache - keep more files open than the system permits SYNOPSIS
no strict 'refs'; use FileCache; # or use FileCache maxopen => 16; cacheout $mode, $path; # or cacheout $path; print $path @data; $fh = cacheout $mode, $path; # or $fh = cacheout $path; print $fh @data; DESCRIPTION
The "cacheout" function will make sure that there's a filehandle open for reading or writing available as the pathname you give it. It automatically closes and re-opens files if you exceed your system's maximum number of file descriptors, or the suggested maximum maxopen. cacheout EXPR The 1-argument form of cacheout will open a file for writing ('>') on it's first use, and appending ('>>') thereafter. Returns EXPR on success for convenience. You may neglect the return value and manipulate EXPR as the filehandle directly if you prefer. cacheout MODE, EXPR The 2-argument form of cacheout will use the supplied mode for the initial and subsequent openings. Most valid modes for 3-argument "open" are supported namely; '>', '+>', '<', '<+', '>>', '|-' and '-|' To pass supplemental arguments to a program opened with '|-' or '-|' append them to the command string as you would system EXPR. Returns EXPR on success for convenience. You may neglect the return value and manipulate EXPR as the filehandle directly if you prefer. CAVEATS
While it is permissible to "close" a FileCache managed file, do not do so if you are calling "FileCache::cacheout" from a package other than which it was imported, or with another module which overrides "close". If you must, use "FileCache::cacheout_close". Although FileCache can be used with piped opens ('-|' or '|-') doing so is strongly discouraged. If FileCache finds it necessary to close and then reopen a pipe, the command at the far end of the pipe will be reexecuted - the results of performing IO on FileCache'd pipes is unlikely to be what you expect. The ability to use FileCache on pipes may be removed in a future release. FileCache does not store the current file offset if it finds it necessary to close a file. When the file is reopened, the offset will be as specified by the original "open" file mode. This could be construed to be a bug. The module functionality relies on symbolic references, so things will break under 'use strict' unless 'no strict "refs"' is also specified. BUGS
sys/param.h lies with its "NOFILE" define on some systems, so you may have to set maxopen yourself. perl v5.16.2 2012-08-26 FileCache(3pm)
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Scalar::Util(3pm) Perl Programmers Reference Guide Scalar::Util(3pm) NAME
Scalar::Util - A selection of general-utility scalar subroutines SYNOPSIS
use Scalar::Util qw(blessed dualvar isweak readonly refaddr reftype tainted weaken); DESCRIPTION
"Scalar::Util" contains a selection of subroutines that people have expressed would be nice to have in the perl core, but the usage would not really be high enough to warrant the use of a keyword, and the size so small such that being individual extensions would be wasteful. By default "Scalar::Util" does not export any subroutines. The subroutines defined are blessed EXPR If EXPR evaluates to a blessed reference the name of the package that it is blessed into is returned. Otherwise "undef" is returned. $scalar = "foo"; $class = blessed $scalar; # undef $ref = []; $class = blessed $ref; # undef $obj = bless [], "Foo"; $class = blessed $obj; # "Foo" dualvar NUM, STRING Returns a scalar that has the value NUM in a numeric context and the value STRING in a string context. $foo = dualvar 10, "Hello"; $num = $foo + 2; # 12 $str = $foo . " world"; # Hello world isvstring EXPR If EXPR is a scalar which was coded as a vstring the result is true. $vs = v49.46.48; $fmt = isvstring($vs) ? "%vd" : "%s"; #true printf($fmt,$vs); isweak EXPR If EXPR is a scalar which is a weak reference the result is true. $ref = $foo; $weak = isweak($ref); # false weaken($ref); $weak = isweak($ref); # true openhandle FH Returns FH if FH may be used as a filehandle and is open, or FH is a tied handle. Otherwise "undef" is returned. $fh = openhandle(*STDIN); # *STDIN $fh = openhandle(*STDIN); # *STDIN $fh = openhandle(*NOTOPEN); # undef $fh = openhandle("scalar"); # undef readonly SCALAR Returns true if SCALAR is readonly. sub foo { readonly($_[0]) } $readonly = foo($bar); # false $readonly = foo(0); # true refaddr EXPR If EXPR evaluates to a reference the internal memory address of the referenced value is returned. Otherwise "undef" is returned. $addr = refaddr "string"; # undef $addr = refaddr $var; # eg 12345678 $addr = refaddr []; # eg 23456784 $obj = bless {}, "Foo"; $addr = refaddr $obj; # eg 88123488 reftype EXPR If EXPR evaluates to a reference the type of the variable referenced is returned. Otherwise "undef" is returned. $type = reftype "string"; # undef $type = reftype $var; # SCALAR $type = reftype []; # ARRAY $obj = bless {}, "Foo"; $type = reftype $obj; # HASH tainted EXPR Return true if the result of EXPR is tainted $taint = tainted("constant"); # false $taint = tainted($ENV{PWD}); # true if running under -T weaken REF REF will be turned into a weak reference. This means that it will not hold a reference count on the object it references. Also when the reference count on that object reaches zero, REF will be set to undef. This is useful for keeping copies of references , but you don't want to prevent the object being DESTROY-ed at its usual time. { my $var; $ref = $var; weaken($ref); # Make $ref a weak reference } # $ref is now undef KNOWN BUGS
There is a bug in perl5.6.0 with UV's that are >= 1<<31. This will show up as tests 8 and 9 of dualvar.t failing COPYRIGHT
Copyright (c) 1997-2001 Graham Barr <gbarr@pobox.com>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. Except weaken and isweak which are Copyright (c) 1999 Tuomas J. Lukka <lukka@iki.fi>. All rights reserved. This program is free software; you can redistribute it and/or mod- ify it under the same terms as perl itself. BLATANT PLUG
The weaken and isweak subroutines in this module and the patch to the core Perl were written in connection with the APress book `Tuomas J. Lukka's Definitive Guide to Object-Oriented Programming in Perl', to avoid explaining why certain things would have to be done in cumber- some ways. perl v5.8.0 2002-06-01 Scalar::Util(3pm)