NAME
Data::Walker - A tool for navigating through Perl data structures
SYNOPSIS
use Data::Walker;
Data::Walker->walk( $data_structure );
# see below for details
DESCRIPTION
This module allows you to "walk" an arbitrary Perl data structure in the
same way that you can walk a directory tree from the command line. It is
meant to be used interactively with a live user, as a command-line
interface.
INSTALLATION
To install this package, just change to the directory which you created
by untarring the package, and type the following:
perl Makefile.PL
make test
make
make install
This will copy Walker.pm to your perl library directory for use by all
perl scripts. You probably must be root to do this, unless you have
installed a personal copy of perl or you have write access to a Perl lib
directory.
USAGE
You open a command-line interface by invoking the cli() function.
use Data::Walker;
Data::Walker->cli( $data_structure );
use Data::Walker;
Data::Walker->cli( $data_structure );
You can customize certain features, like so:
use Data::Walker;
$Data::Walker::Config{'skipdoublerefs'} = 0;
Data::Walker->cli( $data_structure );
If you prefer to use object-style notation, then you can use this syntax
to customize the settings. You can invoke the walk() method directly,
our you can let the cli() method call walk() implicitly:
use Data::Walker;
my $w1 = new Data::Walker;
$w1->walk( $data_structure );
$w1->cli;
my $w2 = new Data::Walker;
$w2->cli( $data_structure );
my $w3 = new Data::Walker( 'skipdoublerefs' => 0 );
$w3->walk( $data_structure );
$w3->cli();
$w3->showrecursion(0);
$w3->cli();
Imagine a data structure like so:
my $s = {
a => [ 10, 20, "thirty" ],
b => {
"w" => "forty",
"x" => "fifty",
"y" => 60,
"z" => \70,
},
c => sub { print "I'm a data structure!\n"; },
d => 80,
};
$s->{e} = \$s->{d};
Here is a sample interactive session examining this structure ('/>' is
the prompt):
/>
/> ls -l
a ARRAY (3)
b HASH (4)
c CODE
d scalar 80
e SCALAR 80
/> cd a
/->{a}> ls -al
.. HASH (5)
. ARRAY (3)
0 scalar 10
1 scalar 20
2 scalar 'thirty'
/->{a}> cd ../b
/->{b}> ls -al
.. HASH (5)
. HASH (4)
w scalar 'forty'
x scalar 'fifty'
y scalar 60
z SCALAR 70
/->{b}> cd ..
/> dump b
dump--> 'b'
$b = {
'x' => 'fifty',
'y' => 60,
'z' => \70,
'w' => 'forty'
};
/> ls -al
.. HASH (5)
. HASH (5)
a ARRAY (3)
b HASH (4)
c CODE
d scalar 80
e SCALAR 80
/> ! $ref->{d} += 3
eval--> $ref->{d} += 3
83
/> ls -al
.. HASH (5)
. HASH (5)
a ARRAY (3)
b HASH (4)
c CODE
d scalar 83
e SCALAR 83
/>
The following commands are available from within the CLI.
With these commands, you can navigate around the data
structure as if it were a directory tree.
cd <target> like UNIX cd
ls like UNIX ls (also respects options -a, -l)
print <target> prints the item as a scalar
dump <target> invokes Data::Dumper
set <key> <value> set configuration variables
show <key> show configuration variables
! or eval eval arbitrary perl (careful!)
help this help message
help set lists the available config variables
For each session (or object) the following items can be configured:
rootname (default: '/' ) displays the root node
refname (default: 'ref' ) displays embedded refs
scalarname (default: 'scalar') displays simple scalars
undefname (default: 'undef' ) displays undefined scalars
maxdepth (default: 1 ) maximum dump-depth (Data::Dumper)
indent (default: 1 ) amount of indent (Data::Dumper)
lscol1width (default: 15 ) column widths for 'ls' displays
lscol2width (default: 25 ) column widths for 'ls' displays
showrecursion (default: 1 ) note recursion in the prompt
showids (default: 0 ) show ref id numbers in ls lists
skipdoublerefs (default: 1 ) hop over ref-to-refs during walks
skipwarning (default: 1 ) warn when hopping over ref-to-refs
truncatescalars (default: 37 ) truncate scalars in 'ls' displays
promptchar (default: '>') customize the session prompt
arrowshaft (default: '-') ('-' in '->')
arrowhead (default: '>') ('>' in '->')
This is an alpha release of this module.
CHANGES
Version 0.16-0.17
The module is now fully object oriented.
This will make it easier to use the module
outside of the CLI.
In the next version, I will completely separate out
the CLI loop, command-parsing regexes, and the functions which
implement the commands. After that, AUTOLOAD can be set up to parse
any commands that the CLI can parse. This will make it
more convenient to use the module from the perl debugger.
NOTE: The walk() function has been separated into two functions,
namely walk() and cli(). The usage instructions have changed.
Please have a look.
Version 0.15
Reorganized the installation tests.
A few minor changes to the module itself.
Version 0.13-0.14
Numerous internal changes:
Moved functionality from the CLI-loop
into distinct functions.
Version 0.12
Blessed references to non-hashes are now handled correctly.
Modified the output of "ls" commands (looks different).
Added new options:
showids, lscol2width, scalarname, undefname,
skipwarning
Numerous internal changes.
Version 0.11
Fixed some misspellings in the help information.
Modified the pretty-print format of scalars.
Added some new comments to the source code.
Various other small updates.
AUTHOR
John Nolan
[email protected] August-December 1999. A copyright statment is
contained within the source code itself.
