NAME
File::Data - interface to file data
DESCRIPTION
Wraps all the accessing of a file into a convenient set of calls for
reading and writing data, including a simple regex interface.
SYNOPSIS
use strict;
use File::Data;
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();
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|key="val"|,
) if $o_sgm;
See the METHODS manpage and the EXAMPLES manpage.
EXPLANATION
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 the same procedure for the umpteenth time 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 @partial = $o_dat->search($pattern);
my $i_cnt = $o_dat->replace($search, $replace);
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.
METHODS
new 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
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.
Each file should have it's own discrete object.
Look in the EXAMPLES manpage for a more complete explanation of
possible arguments to the new() method
read
Read all data from file
my @data = $o_dat->read;
write
Write data to file
my @written = $o_dat->write;
prepend
Prepend to file
my @prepended = $o_dat->prepend(\@lines);
insert
Insert data at line number, starting from '0'
my @inserted = $o_dat->insert($i_lineno, \@lines);
append
Append to file
my @appended = $o_dat->append(\@lines);
search
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 @addrs = $o_dat->search('/^(.*\@.*)$/');
my @names = $o_dat->search('/^(?:[^:]:){4}([^:]+):/');
replace
Replace data in a 'search and replace' manner, returns the final
data.
my @data = $o_dat->replace($search, $replace);
my @data = $o_dat->replace(
q|\ 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?
do Simple wrapper for method calls, returning the object, so that
you can chain them.
my $o_dat = $o_dat->do('insert', @insertargs)->do(\'append', @appendargs)->do('read');
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 the return() entry elsewhere in this document
return
Returns the product of the given (or last) do(), undef on
failure.
my @prepended = $o_dat->PREPEND($a)->APPEND($b)->return('prepend');
my @appended = $o_dat->PREPEND($a)->APPEND($b)->return; # like read()
create
placeholder - unsupported
delete
placeholder - unsupported
info
placeholder - unsupported
VARIABLES
Various variables may be set affecting the behaviour of the module.
$File::Data::DEBUG
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';
$File::Data::FATAL
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
$File::Data::REFERENCE
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 };
$File::Data::SILENT
Set to something other than zero if you don't want error
messages ?-\
$File::Data::SILENT = 0; # per line
$File::Data::STRING
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::Data::PERMISSIONS
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 keys declared below, it will be passed
on to FileHandle and otherwise not modified. We don't support
fancy permission sets.
Read-only permissions may be explicitly set using one of the
following keys:
$File::Data::PERMISSIONS = 'ro'; # or readonly or <
Or, equivalently, for read-write (default):
$File::Data::PERMISSIONS = 'rw'; # or readwrite or +<
# ================================================================
SPECIAL
...
AUTOLOAD
Any unrecognised function will be passed to the FileHandle
object for final consideration, behaviour is then effectively
'o_dat ISA FileHandle'.
$o_dat->truncate;
EXAMPLES
Typical construction examples:
my $o_rw = File::Data->new($filename, 'rw');
my $o_ro = File::Data->new($filename, 'ro');
error
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 the METHOD manpage
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,
});
commandline
From the command line:
Cnew('./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('./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
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.
See the EXAMPLES manpage 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);
UTILITY
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;
AUTHOR
Richard Foley richard.foley@rfi.net 2001
For those that are interested, the docs and tests were (mostly)
written before the code.