If there's anyone out there who is looking for something
to do, this page could use an update to cover the new
[[file]] subcommands introduced in releases 8.3 and 8.4
of Tcl.


  if {([package vcompare [package provide Tcl] 7.6] < 0)
          && [string match unix $tcl_platform(platform)]} {

    # The subcommands copy, delete, rename, and mkdir were added to
    # the Tcl command 'file' in Tcl version 7.6.  The following command
    # approximates them on Unix platforms.  It may not agree with
    # the Tcl 7.6+ command 'file' in all of its functionality (notably
    # the way it reports errors).  Further refinements should be made as
    # needed.
    rename file Tcl7.5_file
    proc file {option args} {
        switch -glob -- $option {
            c* {
                if {[string first $option copy] != 0} {
                    return [uplevel [list Tcl7.5_file $option] $args]
                }
                # Translate -force into -f
                if {[string match -force [lindex $args 0]]} {
                    set args [lreplace $args 0 0 -f]
                }
                uplevel exec cp $args
            }
            de* {
                if {[string first $option delete] != 0} {
                    return [uplevel [list Tcl7.5_file $option] $args]
                }
                if {[string match -force [lindex $args 0]]} {
                    set args [lreplace $args 0 0 -f]
                }
                catch {uplevel exec rm $args}
            }
            mk* {
                if {[string first $option mkdir] != 0} {
                    return [uplevel [list Tcl7.5_file $option] $args]
                }
                uplevel exec mkdir $args
            }
            ren* {
                if {[string first $option rename] != 0} {
                    return [uplevel [list Tcl7.5_file $option] $args]
                }
                if {[string match -force [lindex $args 0]]} {
                    set args [lreplace $args 0 0 -f]
                }
                uplevel exec mv $args
            }
            default {
                uplevel [list Tcl7.5_file $option] $args
            }
        }
    }
  }

  if {[package vcompare [package provide Tcl] 8] < 0} {

    # The subcommands nativename and attributes were added to
    # the Tcl command 'file' in Tcl version 8.0.  Here is an approximation
    # for earlier Tcl versions:
    rename file Tcl7.6_file
    ;proc file {option args} {
        switch -glob -- $option {
            att* {
                if {[string first $option attributes] != 0} {
                    uplevel [list Tcl7.6_file $option] $args
                }
                return -code error "Tcl [package provide Tcl] does not support\
			\[file attributes\].\n\tUpgrade to Tcl 8.0 to use it."
            }
            n* {
                if {[string first $option nativename] != 0} {
                    uplevel [list Tcl7.6_file $option] $args
                }
                if {![llength $args]} {
                    return -code error "wrong # args: should be\
                	    \"file nativename name ?arg ...?\""
                }
                set fcomps [file split [lindex $args 0]]
                # Take care of tilde substitution
                set first [lindex $fcomps 0]
                if {[string match ~* $first]} {
                    set first [file join [file dirname $first] [file tail $first]]
                }
                set result [eval file join [list $first] [lrange $fcomps 1 end]]
                global tcl_platform
                if {[string match windows $tcl_platform(platform)]} {
                    regsub -all -- / $result \\ result
                }
                return $result
            }
            default {
                uplevel [list Tcl7.6_file $option] $args
            }
        }
    }
  }

  if {[package vcompare [package provide Tcl] 8.4] < 0} {
    # The subcommands nativename and attributes were added to
    # the Tcl command 'file' in Tcl version 8.0.  Here is an approximation
    # for earlier Tcl versions:
    rename file Tcl8.0_file
    ;proc file {option args} {
        switch -glob -- $option {
	    norm* {
		set sp [file split [lindex $args 0]]
		if {[file pathtype [lindex $sp 0]] == "relative"} {
		    set sp [file split [eval [list file join [pwd]] $sp]]
		}
		set np {}
		foreach ele $sp {
		    if {$ele != ".."} {
			if {$ele != "."} { lappend np $ele }
		    } elseif {[llength $np]> 1} {
			set np [lrange $np 0 [expr {[llength $np] - 2}]]
		    }
		}
		if {[llength $np] > 0} { return [eval file join $np] }
	    }
	    default {
		uplevel [list Tcl8.0_file $option] $args
	    }
	}
    }
  }

----

The normalize I saw above was purely lexical and did not resolve symlinks. Here is a variant which behaves like the 8.4 file normalize, at least it passes the part of the Tcl testsuite dealing with 'normalize'.

    proc file_ormalize {sp} {
	set sp [file split $sp]

	# Conversion of the incoming path to absolute.
	if {[string equal [file pathtype [lindex $sp 0]] "relative"]} {
	    set sp [file split [eval [list file join [pwd]] $sp]]
	}

	# Resolution of symlink components, and embedded relative
	# modifiers (., and ..).

	set np {}
	while {[llength $sp]} {
	    set ele    [lindex $sp 0]
	    set sp     [lrange $sp 1 end]
	    set islast [expr {[llength $sp] == 0}]

	    if {[string equal $ele ".."]} {
		if {[llength $np] > 1} {
		    # .. : Remove the previous element added to the
		    # new path, if there actually is enough to remove.
		    set np [lrange $np 0 end-1]
		}
	    } elseif {[string equal $ele "."]} {
		# Ignore .'s, they stay at the current location
		continue
	    } else {
		# A regular element. If it is not the last component
		# then check if the combination is a symlink, and if
		# yes, resolve it.

		lappend np $ele

		if {!$islast} {
		    if {[string equal link [file type [set p [eval file join $np]]]]} {
			set dst [file readlink $p]

			# We always push the destination in front of
			# the source path (in expanded form). So that
			# we handle .., .'s, and symlinks inside of
			# this path as well. An absolute path clears
			# the result, a relative one just removes the
			# last, now resolved component.

			set sp [eval [linsert [file split $dst] 0 linsert $sp 0]]

			if {![string equal relative [file pathtype $dst]]} {
			    # Absolute|volrelative destination, clear
			    # result, we have to start over.
			    set np {}
			} else {
			    # Relative link, just remove the resolved
			    # component again.
			    set np [lrange $np 0 end-1]
			}
		    }

		}
	    }
	}
	if {[llength $np] > 0} {
	    return [eval file join $np]
	}
    }

----
[Category Porting]