TIP #431: ADD 'TEMPDIR' SUBCOMMAND TO 'FILE' 
==============================================
 Version:      $Revision: 1.2 $
 Author:       Kevin Pasko <kevin.a.pasko_at_gmail.com>
 State:        Draft
 Type:         Project
 Tcl-Version:  8.6.4
 Vote:         Pending
 Created:      Wednesday, 10 September 2014
 URL:          https://tip.tcl-lang.org431.html
 Post-History: 

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 ABSTRACT 
==========

 This TIP proposes adding a new *tempdir* subcommand to the *file* 
 command, simplifying the effort required in creating uniquely named 
 temporary directories at the scripting level. 

 RATIONALE 
===========

 Due to the non-atomic nature of the *file mkdir* command it is 
 currently impossible to create uniquely named temporary directories at 
 the script level without the possibility of race conditions. 

 SPECIFICATION 
===============

 The *file tempdir* command shall implement the functionality of the 
 POSIX standard mkdtemp() function. With no arguments *file tempdir* 
 shall create a uniquely named temporary directory in the native 
 operating system's temporary directory, with naming convention 
 "*tcl_*/XXXXXX/" where each /X/ is a randomly selected character 
 (following the *file tempfile* naming convention). Successful 
 completion of *file tempdir* shall return the absolute path of the 
 created directory, otherwise an error shall be thrown. 

 *file tempdir* shall have an optional argument, /template/, to modify 
 the created directory's path and name. The /template/ shall be 
 decomposed into (up to) two parts: the directory's path and rootname. 
 If either part is absent, relevant defaults (e.g., according to the 
 native operating system) shall be used. The entire temporary name shall 
 then be formed from the path, the root, and a generated unique string 
 of (typically) six characters. 

 The command syntax should be defined as: 

       *file tempdir* ?/template/? 

 CONSIDERATIONS 
================

     * The subcommand *tempdir* could be a candidate, later, for 
       returning the native file system's temporary directory. Naming 
       the subcommand something else such as *mktempdir* is another 
       option, though strays from the *file tempfile* naming convention. 

     * For future extensibility the *template* argument to *file 
       tempdir* (since it is optional) could be specified in the key / 
       value format, *-template*, changing the command syntax to: 

              *file tempdir* ?/options.../? 

 REFERENCE IMPLEMENTATION 
==========================

 An example of temporary directory creation has already been developed 
 into the Tcl core, at the C level, within the platform specific layers 
 of the *load* command. The principal work remaining is to expose this 
 via a Tcl command. 

 COPYRIGHT 
===========

 This document has been placed in the public domain. 

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