Ken Williams > Path-Class-0.33 > Path::Class::Dir

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Module Version: 0.33   Source  

NAME ^

Path::Class::Dir - Objects representing directories

VERSION ^

version 0.33

SYNOPSIS ^

  use Path::Class;  # Exports dir() by default
  
  my $dir = dir('foo', 'bar');       # Path::Class::Dir object
  my $dir = Path::Class::Dir->new('foo', 'bar');  # Same thing
  
  # Stringifies to 'foo/bar' on Unix, 'foo\bar' on Windows, etc.
  print "dir: $dir\n";
  
  if ($dir->is_absolute) { ... }
  if ($dir->is_relative) { ... }
  
  my $v = $dir->volume; # Could be 'C:' on Windows, empty string
                        # on Unix, 'Macintosh HD:' on Mac OS
  
  $dir->cleanup; # Perform logical cleanup of pathname
  $dir->resolve; # Perform physical cleanup of pathname
  
  my $file = $dir->file('file.txt'); # A file in this directory
  my $subdir = $dir->subdir('george'); # A subdirectory
  my $parent = $dir->parent; # The parent directory, 'foo'
  
  my $abs = $dir->absolute; # Transform to absolute path
  my $rel = $abs->relative; # Transform to relative path
  my $rel = $abs->relative('/foo'); # Relative to /foo
  
  print $dir->as_foreign('Mac');   # :foo:bar:
  print $dir->as_foreign('Win32'); #  foo\bar

  # Iterate with IO::Dir methods:
  my $handle = $dir->open;
  while (my $file = $handle->read) {
    $file = $dir->file($file);  # Turn into Path::Class::File object
    ...
  }
  
  # Iterate with Path::Class methods:
  while (my $file = $dir->next) {
    # $file is a Path::Class::File or Path::Class::Dir object
    ...
  }

DESCRIPTION ^

The Path::Class::Dir class contains functionality for manipulating directory names in a cross-platform way.

METHODS ^

$dir = Path::Class::Dir->new( <dir1>, <dir2>, ... )
$dir = dir( <dir1>, <dir2>, ... )

Creates a new Path::Class::Dir object and returns it. The arguments specify names of directories which will be joined to create a single directory object. A volume may also be specified as the first argument, or as part of the first argument. You can use platform-neutral syntax:

  my $dir = dir( 'foo', 'bar', 'baz' );

or platform-native syntax:

  my $dir = dir( 'foo/bar/baz' );

or a mixture of the two:

  my $dir = dir( 'foo/bar', 'baz' );

All three of the above examples create relative paths. To create an absolute path, either use the platform native syntax for doing so:

  my $dir = dir( '/var/tmp' );

or use an empty string as the first argument:

  my $dir = dir( '', 'var', 'tmp' );

If the second form seems awkward, that's somewhat intentional - paths like /var/tmp or \Windows aren't cross-platform concepts in the first place (many non-Unix platforms don't have a notion of a "root directory"), so they probably shouldn't appear in your code if you're trying to be cross-platform. The first form is perfectly natural, because paths like this may come from config files, user input, or whatever.

As a special case, since it doesn't otherwise mean anything useful and it's convenient to define this way, Path::Class::Dir->new() (or dir()) refers to the current directory (File::Spec->curdir). To get the current directory as an absolute path, do dir()->absolute.

Finally, as another special case dir(undef) will return undef, since that's usually an accident on the part of the caller, and returning the root directory would be a nasty surprise just asking for trouble a few lines later.

$dir->stringify

This method is called internally when a Path::Class::Dir object is used in a string context, so the following are equivalent:

  $string = $dir->stringify;
  $string = "$dir";
$dir->volume

Returns the volume (e.g. C: on Windows, Macintosh HD: on Mac OS, etc.) of the directory object, if any. Otherwise, returns the empty string.

$dir->basename

Returns the last directory name of the path as a string.

$dir->is_dir

Returns a boolean value indicating whether this object represents a directory. Not surprisingly, Path::Class::File objects always return false, and Path::Class::Dir objects always return true.

$dir->is_absolute

Returns true or false depending on whether the directory refers to an absolute path specifier (like /usr/local or \Windows).

$dir->is_relative

Returns true or false depending on whether the directory refers to a relative path specifier (like lib/foo or ./dir).

$dir->cleanup

Performs a logical cleanup of the file path. For instance:

  my $dir = dir('/foo//baz/./foo')->cleanup;
  # $dir now represents '/foo/baz/foo';
$dir->resolve

Performs a physical cleanup of the file path. For instance:

  my $dir = dir('/foo//baz/../foo')->resolve;
  # $dir now represents '/foo/foo', assuming no symlinks

This actually consults the filesystem to verify the validity of the path.

$file = $dir->file( <dir1>, <dir2>, ..., <file> )

Returns a Path::Class::File object representing an entry in $dir or one of its subdirectories. Internally, this just calls Path::Class::File->new( @_ ).

$subdir = $dir->subdir( <dir1>, <dir2>, ... )

Returns a new Path::Class::Dir object representing a subdirectory of $dir.

$parent = $dir->parent

Returns the parent directory of $dir. Note that this is the logical parent, not necessarily the physical parent. It really means we just chop off entries from the end of the directory list until we cain't chop no more. If the directory is relative, we start using the relative forms of parent directories.

The following code demonstrates the behavior on absolute and relative directories:

  $dir = dir('/foo/bar');
  for (1..6) {
    print "Absolute: $dir\n";
    $dir = $dir->parent;
  }
  
  $dir = dir('foo/bar');
  for (1..6) {
    print "Relative: $dir\n";
    $dir = $dir->parent;
  }
  
  ########### Output on Unix ################
  Absolute: /foo/bar
  Absolute: /foo
  Absolute: /
  Absolute: /
  Absolute: /
  Absolute: /
  Relative: foo/bar
  Relative: foo
  Relative: .
  Relative: ..
  Relative: ../..
  Relative: ../../..
@list = $dir->children

Returns a list of Path::Class::File and/or Path::Class::Dir objects listed in this directory, or in scalar context the number of such objects. Obviously, it is necessary for $dir to exist and be readable in order to find its children.

Note that the children are returned as subdirectories of $dir, i.e. the children of foo will be foo/bar and foo/baz, not bar and baz.

Ordinarily children() will not include the self and parent entries . and .. (or their equivalents on non-Unix systems), because that's like I'm-my-own-grandpa business. If you do want all directory entries including these special ones, pass a true value for the all parameter:

  @c = $dir->children(); # Just the children
  @c = $dir->children(all => 1); # All entries

In addition, there's a no_hidden parameter that will exclude all normally "hidden" entries - on Unix this means excluding all entries that begin with a dot (.):

  @c = $dir->children(no_hidden => 1); # Just normally-visible entries
$abs = $dir->absolute

Returns a Path::Class::Dir object representing $dir as an absolute path. An optional argument, given as either a string or a Path::Class::Dir object, specifies the directory to use as the base of relativity - otherwise the current working directory will be used.

$rel = $dir->relative

Returns a Path::Class::Dir object representing $dir as a relative path. An optional argument, given as either a string or a Path::Class::Dir object, specifies the directory to use as the base of relativity - otherwise the current working directory will be used.

$boolean = $dir->subsumes($other)

Returns true if this directory spec subsumes the other spec, and false otherwise. Think of "subsumes" as "contains", but we only look at the specs, not whether $dir actually contains $other on the filesystem.

The $other argument may be a Path::Class::Dir object, a Path::Class::File object, or a string. In the latter case, we assume it's a directory.

  # Examples:
  dir('foo/bar' )->subsumes(dir('foo/bar/baz'))  # True
  dir('/foo/bar')->subsumes(dir('/foo/bar/baz')) # True
  dir('foo/bar' )->subsumes(dir('bar/baz'))      # False
  dir('/foo/bar')->subsumes(dir('foo/bar'))      # False
$boolean = $dir->contains($other)

Returns true if this directory actually contains $other on the filesystem. $other doesn't have to be a direct child of $dir, it just has to be subsumed.

$foreign = $dir->as_foreign($type)

Returns a Path::Class::Dir object representing $dir as it would be specified on a system of type $type. Known types include Unix, Win32, Mac, VMS, and OS2, i.e. anything for which there is a subclass of File::Spec.

Any generated objects (subdirectories, files, parents, etc.) will also retain this type.

$foreign = Path::Class::Dir->new_foreign($type, @args)

Returns a Path::Class::Dir object representing $dir as it would be specified on a system of type $type. Known types include Unix, Win32, Mac, VMS, and OS2, i.e. anything for which there is a subclass of File::Spec.

The arguments in @args are the same as they would be specified in new().

@list = $dir->dir_list([OFFSET, [LENGTH]])

Returns the list of strings internally representing this directory structure. Each successive member of the list is understood to be an entry in its predecessor's directory list. By contract, Path::Class->new( $dir->dir_list ) should be equivalent to $dir.

The semantics of this method are similar to Perl's splice or substr functions; they return LENGTH elements starting at OFFSET. If LENGTH is omitted, returns all the elements starting at OFFSET up to the end of the list. If LENGTH is negative, returns the elements from OFFSET onward except for -LENGTH elements at the end. If OFFSET is negative, it counts backward OFFSET elements from the end of the list. If OFFSET and LENGTH are both omitted, the entire list is returned.

In a scalar context, dir_list() with no arguments returns the number of entries in the directory list; dir_list(OFFSET) returns the single element at that offset; dir_list(OFFSET, LENGTH) returns the final element that would have been returned in a list context.

$dir->components

Identical to c<dir_list()>. It exists because there's an analogous method dir_list() in the Path::Class::File class that also returns the basename string, so this method lets someone call components() without caring whether the object is a file or a directory.

$fh = $dir->open()

Passes $dir to IO::Dir->open and returns the result as an IO::Dir object. If the opening fails, undef is returned and $! is set.

$dir->mkpath($verbose, $mode)

Passes all arguments, including $dir, to File::Path::mkpath() and returns the result (a list of all directories created).

$dir->rmtree($verbose, $cautious)

Passes all arguments, including $dir, to File::Path::rmtree() and returns the result (the number of files successfully deleted).

$dir->remove()

Removes the directory, which must be empty. Returns a boolean value indicating whether or not the directory was successfully removed. This method is mainly provided for consistency with Path::Class::File's remove() method.

$dir->tempfile(...)

An interface to File::Temp's tempfile() function. Just like that function, if you call this in a scalar context, the return value is the filehandle and the file is unlinked as soon as possible (which is immediately on Unix-like platforms). If called in a list context, the return values are the filehandle and the filename.

The given directory is passed as the DIR parameter.

Here's an example of pretty good usage which doesn't allow race conditions, won't leave yucky tempfiles around on your filesystem, etc.:

  my $fh = $dir->tempfile;
  print $fh "Here's some data...\n";
  seek($fh, 0, 0);
  while (<$fh>) { do something... }

Or in combination with a fork:

  my $fh = $dir->tempfile;
  print $fh "Here's some more data...\n";
  seek($fh, 0, 0);
  if ($pid=fork()) {
    wait;
  } else {
    something($_) while <$fh>;
  }
$dir_or_file = $dir->next()

A convenient way to iterate through directory contents. The first time next() is called, it will open() the directory and read the first item from it, returning the result as a Path::Class::Dir or Path::Class::File object (depending, of course, on its actual type). Each subsequent call to next() will simply iterate over the directory's contents, until there are no more items in the directory, and then the undefined value is returned. For example, to iterate over all the regular files in a directory:

  while (my $file = $dir->next) {
    next unless -f $file;
    my $fh = $file->open('r') or die "Can't read $file: $!";
    ...
  }

If an error occurs when opening the directory (for instance, it doesn't exist or isn't readable), next() will throw an exception with the value of $!.

$dir->traverse( sub { ... }, @args )

Calls the given callback for the root, passing it a continuation function which, when called, will call this recursively on each of its children. The callback function should be of the form:

  sub {
    my ($child, $cont, @args) = @_;
    # ...
  }

For instance, to calculate the number of files in a directory, you can do this:

  my $nfiles = $dir->traverse(sub {
    my ($child, $cont) = @_;
    return sum($cont->(), ($child->is_dir ? 0 : 1));
  });

or to calculate the maximum depth of a directory:

  my $depth = $dir->traverse(sub {
    my ($child, $cont, $depth) = @_;
    return max($cont->($depth + 1), $depth);
  }, 0);

You can also choose not to call the callback in certain situations:

  $dir->traverse(sub {
    my ($child, $cont) = @_;
    return if -l $child; # don't follow symlinks
    # do something with $child
    return $cont->();
  });
$dir->traverse_if( sub { ... }, sub { ... }, @args )

traverse with additional "should I visit this child" callback. Particularly useful in case examined tree contains inaccessible directories.

Canonical example:

  $dir->traverse_if(
    sub {
       my ($child, $cont) = @_;
       # do something with $child
       return $cont->();
    }, 
    sub {
       my ($child) = @_;
       # Process only readable items
       return -r $child;
    });

Second callback gets single parameter: child. Only children for which it returns true will be processed by the first callback.

Remaining parameters are interpreted as in traverse, in particular traverse_if(callback, sub { 1 }, @args is equivalent to traverse(callback, @args).

$dir->recurse( callback => sub {...} )

Iterates through this directory and all of its children, and all of its children's children, etc., calling the callback subroutine for each entry. This is a lot like what the File::Find module does, and of course File::Find will work fine on Path::Class objects, but the advantage of the recurse() method is that it will also feed your callback routine Path::Class objects rather than just pathname strings.

The recurse() method requires a callback parameter specifying the subroutine to invoke for each entry. It will be passed the Path::Class object as its first argument.

recurse() also accepts two boolean parameters, depthfirst and preorder that control the order of recursion. The default is a preorder, breadth-first search, i.e. depthfirst => 0, preorder => 1. At the time of this writing, all combinations of these two parameters are supported except depthfirst => 0, preorder => 0.

callback is normally not required to return any value. If it returns special constant Path::Class::Entity::PRUNE() (more easily available as $item-PRUNE>), no children of analyzed item will be analyzed (mostly as if you set $File::Find::prune=1). Of course pruning is available only in preorder, in postorder return value has no effect.

$st = $file->stat()

Invokes File::stat::stat() on this directory and returns a File::stat object representing the result.

$st = $file->lstat()

Same as stat(), but if $file is a symbolic link, lstat() stats the link instead of the directory the link points to.

$class = $file->file_class()

Returns the class which should be used to create file objects.

Generally overridden whenever this class is subclassed.

AUTHOR ^

Ken Williams, kwilliams@cpan.org

SEE ALSO ^

Path::Class, Path::Class::File, File::Spec

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