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Path::Class::Dir(3) |
User Contributed Perl Documentation |
Path::Class::Dir(3) |
Path::Class::Dir - Objects representing directories
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
...
}
The "Path::Class::Dir" class contains
functionality for manipulating directory names in a cross-platform way.
- $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/..')->subsumes(dir('foo/../bar)) # True
dir('foo/bar' )->subsumes(dir('bar/baz')) # False
dir('/foo/bar')->subsumes(dir('foo/bar')) # False
dir('foo/..')->subsumes(dir('bar')) # False! Use C<contains> to resolve ".."
- $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 after both paths
have been resolved.
- $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 "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 "unlink"ed 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.
Ken Williams, kwilliams@cpan.org
Path::Class, Path::Class::File, File::Spec
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