File::Data - 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 METHODS and EXAMPLES.
lowercase method calls return the object itself, so you can chain calls.
my $o_obj = $o_dat->read; # ! <= object !
UPPERCASE 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 much more efficient, and I'll be very interested to try and incorporate any suggestions to that effect. Note though that the intention has been to create a simple moderately consistent interface, rather than a complicated one. Sometimes it's better to roll your own, and sometimes you don't have to reinvent the wheel - TMTOWTDI.
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 EXAMPLES 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;
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
Close the file
my $i_closed = $o_dat->close; # 1|0
Various variables may be set affecting the behaviour of the module.
Set to 0 (default) or 1 for debugging information to be printed on STDOUT.
$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 ISA 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 STDERR, unless warnings are declared fatal, in which case we croak. You can register your own error handlers for any method mentioned in the METHOD 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 STDOUT
$o_dat->_debug($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 STDERR, will croak if File::Data::FATAL set, returning ().
See EXAMPLES 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);
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;
Richard Foley <C> richard.foley@rfi.net 2001
For those that are interested, the docs and tests were (mostly) written before the code, which was helpful in keeping it tidy.
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()
4 POD Errors
The following errors were encountered while parsing the POD:
You forgot a '=back' before '=head1'
You can't have =items (as at line 873) unless the first thing after the =over is an =item
You can't have =items (as at line 1184) unless the first thing after the =over is an =item
'=item' outside of any '=over'
=over without closing =back
To install File::Data, copy and paste the appropriate command in to your terminal.
cpanm
cpanm File::Data
CPAN shell
perl -MCPAN -e shell install File::Data
For more information on module installation, please visit the detailed CPAN module installation guide.