Tmppath(3C++)

Synopsis

   #include <Path.h>
   class Tmppath : public Path{
   public:
   //  Constructors
       Tmppath();
       Tmppath(const char* pfx,const char* ext = ");
       Tmppath(const Path& dir);
       Tmppath(const Path& dir,const char* pfx,
           const char* ext = ");
   //  Implicit arguments
       static void use(const char* pfx);
       static void use(const Path& dir);
       static void use(const Path& dir,const char* pfx);
       static void use();
   };

Description

A Tmppath is just like a Path (see Path(3C++)), except it is initialized to a Path corresponding to a file which does not currently exist in the underlying file system. Tmppath should replace mktemp(3), tempnam(3) and tmpnam(3) in most C++ applications.

Constructors

Tmppath(); The dirname of the constructed path is the first directory in the following list for which a Path corresponding to a non-existent file can be constructed: (1) the current value of the environment variable TMPDIR, if TMPDIR is set and is other than the empty string; (2) "/usr/tmp"; (3) "/tmp". If a Path corresponding to a non-existent file cannot be constructed, then Path(".") is constructed. The dirname of the constructed Path is not checked for existence. In particular, if TMPDIR does not exist in the underlying file system, then TMPDIR will be used, and any attempt to open the resulting Tmppath will fail. (Not checking the existence of the directory is done for efficiency reasons when constructing many Tmppath's.)

Tmppath(const char* pfx,const char* ext = ); Same as above, except the basename of the constructed Path begins with the prefix pfx, and ends with the suffix ext.

Tmppath(const Path& dir);

Tmppath(const Path& dir,const char* pfx, const char* ext = ); Same as the above two constructors respectively, except dir is used as the dirname of the constructed Path. None of the other directories are tried.

Implicit arguments

These functions make it possible to specify once and for all a default directory and/or prefix to be used in all future Tmppath constructions. Individual constructions are still free to override these defaults by supplying explicit values for these arguments. These functions should not be called during static initialization.

static void use(const char* pfx); pfx is an implicit argument to all future constructions lacking that argument. Future calls to other constructors have their original meanings.

static void use(const Path& dir); dir is an implicit argument to all future constructions lacking that argument. Future calls to other constructors have their original meanings.

static void use(const Path& dir,const char* pfx); dir and pfx are implicit arguments to all future constructions lacking either of those arguments.

static void use(); Future calls to constructors have their original meanings.

Warnings

It is completely up to the programmer to prevent the race between constructing a Tmppath and opening it for writing. As usual, the easiest way of guaranteeing no race is to use tmpfile(3).

An attempt to open a Tmppath can fail either if the program has lost the construct/open race, or the directory corresponding to the dirname of the Tmppath does not exist in the underlying file system.

The Tmppath constructor is subtly overloaded. Beware.

References

   mktemp(3)
   tempnam(3)
   tmpfile(3)
   tmpnam(3)
   Path(3C++)
   Search_path(3C++)