TIP #210: ADD 'TEMPFILE' SUBCOMMAND TO 'FILE' 
===============================================
 Version:      $Revision: 1.11 $
 Author:       Bob Techentin <techentin.robert_at_mayo.edu>
               Donal K. Fellows <donal.k.fellows_at_manchester.ac.uk>
 State:        Final
 Type:         Project
 Tcl-Version:  8.6
 Vote:         Done
 Created:      Monday, 19 July 2004
 URL:          https://tip.tcl-lang.org210.html
 Post-History: 

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 ABSTRACT 
==========

 Programmers often need to create temporary files. This TIP proposes 
 adding the new subcommand *tempfile* to the *file* command, simplifying 
 programmer effort in creating a unique temporary file name. 

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

 Creating temporary files is a primitive and common enough operation 
 that the ANSI C standard defines several subroutines to assist 
 programmers. The /tmpnam()/ function generates a string that is a valid 
 file name that is not the name of an existing file. The /tmpfile()/ 
 function returns a valid file pointer to a temporary file that is 
 removed automatically when it is closed or at program termination. Both 
 functions are commonly used by programmers, without worrying about the 
 optimal location for temporary files or schemes required to create 
 unique file names. 

 Tcl has not supported temporary files, so programmers have had to write 
 code to generate unique file names and choose locations like //tmp/ or 
 /C:\temp/. The /fileutil/ module of tcllib provides a relatively 
 sophisticated implementation of /tempfile/, but extension writers have 
 not been able to rely on this code. Modules in Iwidgets, the Tcl 
 plugin, tcllib, and TclX all appear to have this sort of code, and not 
 all are correct. 

 This TIP proposes to extend the *file* command with one subcommand to 
 generate temporary files and file names. By extending the core command, 
 application programmers and extension writers will be able to depend on 
 this functionality for their code, without resorting to copying or 
 depending on tcllib. 

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

 This TIP proposes an extension to the *file* command, implementing the 
 functionality of the POSIX standard mkstemp() function. The new 
 subcommand will be called *tempfile*. It will return an open file 
 channel, and (optionally) the name of the temporary file. 

 SYNOPSIS 
==========

       *file tempfile* ?/namevar/? ?/template/? 

 Opens a unique temporary file and returns an open file channel. If 
 /namevar/ is specified, then the command will set the variable to the 
 name of the temporary file. If the /template/ string is specified, it 
 will be decomposed into (up to) three parts: the path, the root, and 
 the extension. Any part may be absent. If the path or root are absent, 
 system-dependent defaults will be used. If the extension is absent, no 
 extension will be used. The temporary name will then be formed from the 
 path, the root, some unique string, and the extension (if defined). 

 The returned channel will have been opened in read-write mode (but not 
 append mode) using the defaults for EOL translation, encoding, etc. 

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

 Available as Tcl Patch #999162 on SourceForge 
 [<URL:https://sourceforge.net/support/tracker.php?aid=999162>]. /(That 
 patch is for an old version of the TIP.)/ 

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

 This document has been placed in the public domain. 

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