Interface to file data
Wraps all the accessing of a file into a convenient set of calls for reading and writing data, including a simple regex interface.
Note that the file needs to exist prior to using this module!
See new()
use strict;
use File::Data;
my $o_dat = File::Data->new('./t/example');
$o_dat->write("complete file contents\n");
$o_dat->prepend("first line\n"); # line 0
$o_dat->append("original second (last) line\n");
$o_dat->insert(2, "new second line\n"); # inc. zero!
$o_dat->replace('line', 'LINE');
print $o_dat->READ;
Or, perhaps more seriously :-} my $o_sgm = File::Data->new('./sgmlfile');
print "new SGML data: ".$o_sgm->REPLACE( '\<\s*((?i)tag)\s*\>\s*((?s).*)\s*\<\s*((?i)\s*\/\s*tag)\s*\>', qq|<tag>key="val"</tag>|, ) if $o_sgm; See \s-1METHODS\s0 and \s-1EXAMPLES\s0.
lowercase method calls return the object itself, so you can chain calls.
my $o_obj = $o_dat->read; # ! <= object !
\s-1UPPERCASE\s0 method calls return the data relevant to the operation.
my @data = $o_dat->READ; # ! <= data !
While this may occasionally be frustrating, using the principle of least surprise, it is at least consistent.
See do
The idea is to standardise accessing of files for repetitive and straight forward tasks, and remove the repeated and therefore error prone file access I have seen in many sites, where varying, (with equivalently varying success), methods are used to achieve essentially the same result - a simple search and replace and/or a regex match. Approaches to opening and working with files vary so much, where one person may wish to know if a file exists, another wishes to know whether the target is a file, or if it is readable, or writable and so on. Sometimes, in production code even (horror), file's are opened without any checks of whether the open was succesful. Then there's a loop through each line to find the first or many patterns to read and/or replace. With a failure, normally the only message is 'permission denied', is that read or write access, does the file even exist? etc. This module attempts to provide a plain/generic interface to accessing a file's data. This will not suit every situation, but I have included some examples which will hopefully demonstrate that it may be used in situations where people would normally go through varying and inconsistent, (and therefore error-prone), procedures - to get at the same data. Theoretically you can mix and match your read and writes so long as you don't open read-only. my $o_dat = File::Data->new($file);
my $i_snrd = $o_dat->append($append)->REPLACE($search, $replace);
print $o_dat->READ; One last thing - I'm sure this could be made more efficient, and I'd be receptive to any suggestions to that effect. Note though that the intention has been to create a simple and consistent interface, rather than a complicated one.
Create a new File::Data object (default read-write). my $o_rw = File::Data->new($filename); # read-write
my $o_ro = File::Data->new($filename, 'ro'); # read-only Each file should have it's own discrete object. Note that if you open a file read-only and then attempt to write to it, that will be regarded as an error, even if you change the permissions in the meantime. Further: The file must exist before succesful use of this method is possible. This is not a replacement for modules which create and delete files, this is purely designed as an interface to the data of existing files. A create function is a future possibility. Look in \s-1EXAMPLES\s0 for a more complete explanation of possible arguments to the new() method
Read all data from file $o_dat = $o_dat->read; # !
my @data = $o_dat->READ;
read does this...
Write data to file my $o_dat = $o_dat->WRITE; # !
my @written = $o_dat->write;
Prepend to file my $o_dat = $o_dat->prepen(\@lines); # !
my @prepended = $o_dat->prepend(\@lines);
Insert data at line number, starting from '0' my $o_dat = $o_dat->insert($i_lineno, \@lines); # !
my @inserted = $o_dat->INSERT($i_lineno, \@lines);
Append to file my $o_dat = $o_dat->append(\@lines); # !
my @appended = $o_dat->APPEND(\@lines);
Retrieve data out of a file, simple list of all matches found are returned. Note - you must use capturing parentheses for this to work! my $o_dat = $o_dat->search('/^(.*\@.*)$/'); # !
my @addrs = $o_dat->SEARCH('/^(.*\@.*)$/');
my @names = $o_dat->SEARCH('/^(?:[^:]:){4}([^:]+):/');
Replace data in a 'search and replace' manner, returns the final data. my $o_dat = $o_dat->replace($search, $replace); # !
my @data = $o_dat->REPLACE($search, $replace);
my @data = $o_dat->REPLACE( q|\<a href=(['"])([^$1]+)?$1| => q|'my.sales.com'|, ); This is simple, in that you can do almost anything in the search side, but the replace side is a bit more restricted, as we can't effect the replacement modifiers on the fly. If you really need this, perhaps (?{}) can help?
Returns the product of the given (or last) do(), undef on failure. my $o_dat = $o_dat->prepend($A)->append($b)->return('prepend'); # !
my @prepended = $o_dat->prepend($A)->append($b)->RETURN('prepend');
my @appended = $o_dat->prepend($A)->append($b)->RETURN; # like read()
placeholder - unsupported
placeholder - unsupported
Close the file my $i_closed = $o_dat->close; # 1|0
placeholder - unsupported
Various variables may be set affecting the behaviour of the module. Set to 0 (default) or 1 for debugging information to be printed on \s-1STDOUT\s0. $File::Data::DEBUG = 1; Alternatively set to a regex of any of the prime methods to debug them individually. $File::Data::DEBUG = '(ap|pre)pend'; Will die if there is any failure in accessing the file, or reading the data. Default = 0 (don't die - just warn); $File::Data::FATAL = 1; # die Will return a reference, not a list, useful with large files. Default is 0, ie; methods normally returns a list. Hopefully future versions of perl may return a reference if you request one, but as this is not supported generically yet, nor do we, so we require the variable to be set. There may be an argument to make this a reference by default, feedback will decide. $File::Data::REFERENCE = 1;
my $a_ref = $o_dat->search('.*');
print "The log: \n".@{ $a_ref }; Set to something other than zero if you don't want error messages ?-\ $File::Data::SILENT = 0; # per line Where regex's are used, default behaviour is to treate the entire file as a single scalar string, so that, for example, (?ms:...) matches are effective. Unset if you don't want this behaviour. $File::Data::STRING = 0; # per line File will be opened read-write (insert() compatible) unless this variable is set explicitly or given via new(). In either case, unless it is one of our valid permission keys declared below, it will be passed on to FileHandle and otherwise not modified. We don't support fancy permission sets, just read or write. Read-only permissions may be explicitly set using one of these keys: $File::Data::PERMISSIONS = 'ro'; # or readonly or < Or, equivalently, for read-write (default): $File::Data::PERMISSIONS = 'rw'; # or readwrite or +< Note that it makes no sense to have an 'append only' command (>>), we'd have to disable all of write, search and replace, and insert, etc. in that case - just use the append() method only. This is a KISS-compatible module remember?
# ================================================================
...
Any unrecognised function will be passed to the FileHandle object for final consideration, behaviour is then effectively 'o_dat \s-1ISA\s0 FileHandle'. $o_dat->truncate;
Typical construction examples:
my $o_rw = File::Data->new($filename, 'rw');
my $o_ro = File::Data->new($filename, 'ro');
my $o_dat = File::Data->new('./jabber');
$o_dat->write(" Bewxre the Jabberwock my son,\n");
$o_dat->prepend("The Jxbberwock by Lewis Cxrroll:\n");
$o_dat->append(" the claws thxt snxtch,\n ...\n");
$o_dat->insert(2, " the jaws which bite.\n");
$o_dat->replace('x', 'a');
print $o_dat->SEARCH('The.+\n')->REPLACE("The.+\n", '')->return('search');
print $o_dat->READ;
Failure is indicated by an error routine being called, this will print out any error to \s-1STDERR\s0, unless warnings are declared fatal, in which case we croak. You can register your own error handlers for any method mentioned in the \s-1METHOD\s0 section of this document, in addition is a special init call for initial file opening and general setting up. Create a read-write object with a callback for all errors: my $o_rw = File::Data->new($filename, 'ro', { 'error' => \&myerror, }); Create a read-only object with a separate object handler for each error type: my $o_rw = File::Data->new($filename, 'rw', { 'error' => $o_generic->error_handler, 'insert' => $o_handler->insert_error, 'open' => $o_open_handler, 'read' => \&carp, 'write' => \&write_error, });
From the command line: C<perl -MFile::Data -e "File::Data->new('./test.txt')->write('some stuff')"> And (very non-obfuscated) C< perl -MFile::Data -e "@x=sort qw(perl another hacker just); print map {split(\"\n\", ucfirst(\$_).\" \")}\ File::Data->new(\"./t/japh\")->\ write(shift(@x).\"\n\")-> \ append(shift(@x).\"\n\")-> \ prepend(shift(@x).\"\n\")-> \ insert(2, shift(@x).\"\n\")->\ READ;" > If you still have problems, mail me the output of make test TEST_VERBOSE=1
Private methods not expected to be called by anybody, and completely unsupported. Expected to metamorphose regularly - do not call these - you have been warned! _var Variable get/set method my $get = $o_dat->_var($key); # get
my $set = $o_dat->_var($key, $val); # set _debug Print given args on \s-1STDOUT\s0 $o_dat->_debug($msg) if $File::Data::DEBUG; _vars Return dumped env and object key and values print $o_dat->_vars; _err Get/set error handling methods/objects my $c_sub = $o_dat->_err('insert'); # or default _error By default prints error to \s-1STDERR\s0, will croak if File::Data::FATAL set, returning (). See \s-1EXAMPLES\s0 for info on how to pass your own error handlers in. _mapfile Maps file my $file = $o_dat->_mapfile($filename); _mapperms Maps given permissions to appropriate form for FileHandle my $perms = $o_dat->_mapperms('+<'); _maperrs Map error handlers, if given my $h_errs = $o_dat->_maperrs(\%error_handlers); _enter Mark the entering of a special section, or state my $entered = $o_dat->enter('search'); _leave Mark the leaving of a special section, or state my $left = $o_dat->_leave('search'); _fh Get and set FileHandle. Returns undef otherwise. my $FH = $o_dat->_fh($FH);
Private methods not expected to be called by anybody, and completely unsupported.
Expected to metamorphose regularly - do not call these - you have been warned!
The following utility methods return integer values 1 = success
0 = failure _init Setup object, open a file, with permissions. my $i_ok = $o_date->_init($file, $perm, $h_errs); _check_access Checks the args for existence and appropriate permissions etc. my $i_isok = $o_dat->_check_access($filename, $permissions); _open Open the file my $i_ok = $o_dat->_open; _lock Lock the file my $i_ok = $o_dat->_lock; _unlock Unlock the file my $i_ok = $o_dat->_unlock; _close Close the filehandle my $i_ok = $o_dat->_close; do Simple wrapper for method calls, returning the content. my @inserted = $o_dat->do('insert', @this);
my @appended = $o_dat->do('append', @this); An addendum to this method, and to make life generally easier, is that you can also call any of the above methods in uppercase, to call via do() eg; my @data = $o_dat->WRITE($this)->APPEND->($that)->read; First argument is the method to call, followed by the arguments that method expects. perl -MFile::Data -e "print File::Data->new($file)->INSERT(3, \"third line\n\")->READ"; If you want to get at the output of a particular called method see return()
Copyright 2012 by Richard Foley <[email protected]>
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
See http://www.perl.com/perl/misc/Artistic.html
Hey! The above document had some coding errors, which are explained below:
You forgot a '=back' before '=head1'
You can't have =items (as at line 878) unless the first thing after the =over is an =item
You can't have =items (as at line 1189) unless the first thing after the =over is an =item