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NAMEURI::file - URI that maps to local file namesSYNOPSISuse URI::file; $u1 = URI->new("file:/foo/bar"); $u2 = URI->new("foo/bar", "file"); $u3 = URI::file->new($path); $u4 = URI::file->new("c:\\windows\\", "win32"); $u1->file; $u1->file("mac"); DESCRIPTIONThe "URI::file" class supports "URI" objects belonging to the file URI scheme. This scheme allows us to map the conventional file names found on various computer systems to the URI name space. An old specification of the file URI scheme is found in RFC 1738. Some older background information is also in RFC 1630. There are no newer specifications as far as I know.If you simply want to construct file URI objects from URI strings, use the normal "URI" constructor. If you want to construct file URI objects from the actual file names used by various systems, then use one of the following "URI::file" constructors:
The following methods are supported for file URI (in addition to the common and generic methods described in URI):
The "URI::file" module can be used to map generic file names to names suitable for the current system. As such, it can work as a nice replacement for the "File::Spec" module. For instance, the following code translates the UNIX-style file name Foo/Bar.pm to a name suitable for the local system: $file = URI::file->new("Foo/Bar.pm", "unix")->file; die "Can't map filename Foo/Bar.pm for $^O" unless defined $file; open(FILE, $file) || die "Can't open '$file': $!"; # do something with FILE MAPPING NOTESMost computer systems today have hierarchically organized file systems. Mapping the names used in these systems to the generic URI syntax allows us to work with relative file URIs that behave as they should when resolved using the generic algorithm for URIs (specified in RFC 2396). Mapping a file name to the generic URI syntax involves mapping the path separator character to "/" and encoding any reserved characters that appear in the path segments of the file name. If path segments consisting of the strings "." or ".." have a different meaning than what is specified for generic URIs, then these must be encoded as well.If the file system has device, volume or drive specifications as the root of the name space, then it makes sense to map them to the authority field of the generic URI syntax. This makes sure that relative URIs can not be resolved "above" them, i.e. generally how relative file names work in those systems. Another common use of the authority field is to encode the host on which this file name is valid. The host name "localhost" is special and generally has the same meaning as a missing or empty authority field. This use is in conflict with using it as a device specification, but can often be resolved for device specifications having characters not legal in plain host names. File name to URI mapping in normally not one-to-one. There are usually many URIs that map to any given file name. For instance, an authority of "localhost" maps the same as a URI with a missing or empty authority. Example 1: The Mac classic (Mac OS 9 and earlier) used ":" as path separator, but not in the same way as a generic URI. ":foo" was a relative name. "foo:bar" was an absolute name. Also, path segments could contain the "/" character as well as the literal "." or "..". So the mapping looks like this: Mac classic URI ---------- ------------------- :foo:bar <==> foo/bar : <==> ./ ::foo:bar <==> ../foo/bar ::: <==> ../../ foo:bar <==> file:/foo/bar foo:bar: <==> file:/foo/bar/ .. <==> %2E%2E <undef> <== / foo/ <== file:/foo%2F ./foo.txt <== file:/.%2Ffoo.txt Note that if you want a relative URL, you *must* begin the path with a :. Any path that begins with [^:] is treated as absolute. Example 2: The UNIX file system is easy to map, as it uses the same path separator as URIs, has a single root, and segments of "." and ".." have the same meaning. URIs that have the character "\0" or "/" as part of any path segment can not be turned into valid UNIX file names. UNIX URI ---------- ------------------ foo/bar <==> foo/bar /foo/bar <==> file:/foo/bar /foo/bar <== file://localhost/foo/bar file: ==> ./file: <undef> <== file:/fo%00/bar / <==> file:/ CONFIGURATION VARIABLESThe following configuration variables influence how the class and its methods behave:
SEE ALSOURI, File::Spec, perlportCOPYRIGHTCopyright 1995-1998,2004 Gisle Aas.This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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