File::Spec::Mac - File::Spec for Mac OS (Classic)
require File::Spec::Mac; # Done internally by File::Spec if neededMethods for manipulating file specifications.
On Mac OS, there's nothing to be done. Returns what it's given.
Concatenate two or more directory names to form a path separated by colons (":") ending with a directory. Resulting paths are relative by default, but can be forced to be absolute (but avoid this, see below). Automatically puts a trailing ":" on the end of the complete path, because that's what's done in MacPerl's environment and helps to distinguish a file path from a directory path.
IMPORTANT NOTE: Beginning with version 1.3 of this module, the resulting path is relative by default and not absolute. This decision was made due to portability reasons. Since File::Spec->catdir() returns relative paths on all other operating systems, it will now also follow this convention on Mac OS. Note that this may break some existing scripts.
The intended purpose of this routine is to concatenate directory names. But because of the nature of Macintosh paths, some additional possibilities are allowed to make using this routine give reasonable results for some common situations. In other words, you are also allowed to concatenate paths instead of directory names (strictly speaking, a string like ":a" is a path, but not a name, since it contains a punctuation character ":").
So, beside calls like
catdir("a") = ":a:"
catdir("a","b") = ":a:b:"
catdir() = "" (special case)calls like the following
catdir(":a:") = ":a:"
catdir(":a","b") = ":a:b:"
catdir(":a:","b") = ":a:b:"
catdir(":a:",":b:") = ":a:b:"
catdir(":") = ":"are allowed.
Here are the rules that are used in catdir(); note that we try to be as compatible as possible to Unix:
The resulting path is relative by default, i.e. the resulting path will have a leading colon.
A trailing colon is added automatically to the resulting path, to denote a directory.
Generally, each argument has one leading ":" and one trailing ":" removed (if any). They are then joined together by a ":". Special treatment applies for arguments denoting updir paths like "::lib:", see (4), or arguments consisting solely of colons ("colon paths"), see (5).
When an updir path like ":::lib::" is passed as argument, the number of directories to climb up is handled correctly, not removing leading or trailing colons when necessary. E.g.
catdir(":::a","::b","c") = ":::a::b:c:"
catdir(":::a::","::b","c") = ":::a:::b:c:"Adding a colon ":" or empty string "" to a path at any position doesn't alter the path, i.e. these arguments are ignored. (When a "" is passed as the first argument, it has a special meaning, see (6)). This way, a colon ":" is handled like a "." (curdir) on Unix, while an empty string "" is generally ignored (see Unix->canonpath() ). Likewise, a "::" is handled like a ".." (updir), and a ":::" is handled like a "../.." etc. E.g.
catdir("a",":",":","b") = ":a:b:"
catdir("a",":","::",":b") = ":a::b:"If the first argument is an empty string "" or is a volume name, i.e. matches the pattern /^[^:]+:/, the resulting path is absolute.
Passing an empty string "" as the first argument to catdir() is like passingFile::Spec->rootdir() as the first argument, i.e.
catdir("","a","b") is the same as
catdir(rootdir(),"a","b").This is true on Unix, where catdir("","a","b") yields "/a/b" and rootdir() is "/". Note that rootdir() on Mac OS is the startup volume, which is the closest in concept to Unix' "/". This should help to run existing scripts originally written for Unix.
For absolute paths, some cleanup is done, to ensure that the volume name isn't immediately followed by updirs. This is invalid, because this would go beyond "root". Generally, these cases are handled like their Unix counterparts:
Unix:
Unix->catdir("","") = "/"
Unix->catdir("",".") = "/"
Unix->catdir("","..") = "/" # can't go
# beyond root
Unix->catdir("",".","..","..","a") = "/a"
Mac:
Mac->catdir("","") = rootdir() # (e.g. "HD:")
Mac->catdir("",":") = rootdir()
Mac->catdir("","::") = rootdir() # can't go
# beyond root
Mac->catdir("",":","::","::","a") = rootdir() . "a:"
# (e.g. "HD:a:")However, this approach is limited to the first arguments following "root" (again, see Unix->canonpath() ). If there are more arguments that move up the directory tree, an invalid path going beyond root can be created.
As you've seen, you can force catdir() to create an absolute path by passing either an empty string or a path that begins with a volume name as the first argument. However, you are strongly encouraged not to do so, since this is done only for backward compatibility. Newer versions of File::Spec come with a method called catpath() (see below), that is designed to offer a portable solution for the creation of absolute paths. It takes volume, directory and file portions and returns an entire path. While catdir() is still suitable for the concatenation of directory names, you are encouraged to use catpath() to concatenate volume names and directory paths. E.g.
$dir = File::Spec->catdir("tmp","sources");
$abs_path = File::Spec->catpath("MacintoshHD:", $dir,"");yields
"MacintoshHD:tmp:sources:" .Concatenate one or more directory names and a filename to form a complete path ending with a filename. Resulting paths are relative by default, but can be forced to be absolute (but avoid this).
IMPORTANT NOTE: Beginning with version 1.3 of this module, the resulting path is relative by default and not absolute. This decision was made due to portability reasons. Since File::Spec->catfile() returns relative paths on all other operating systems, it will now also follow this convention on Mac OS. Note that this may break some existing scripts.
The last argument is always considered to be the file portion. Since catfile() uses catdir() (see above) for the concatenation of the directory portions (if any), the following with regard to relative and absolute paths is true:
catfile("") = ""
catfile("file") = "file"but
catfile("","") = rootdir() # (e.g. "HD:")
catfile("","file") = rootdir() . file # (e.g. "HD:file")
catfile("HD:","file") = "HD:file"This means that catdir() is called only when there are two or more arguments, as one might expect.
Note that the leading ":" is removed from the filename, so that
catfile("a","b","file") = ":a:b:file" and
catfile("a","b",":file") = ":a:b:file"give the same answer.
To concatenate volume names, directory paths and filenames, you are encouraged to use catpath() (see below).
Returns a string representing the current directory. On Mac OS, this is ":".
Returns a string representing the null device. On Mac OS, this is "Dev:Null".