Writting an editor

Writting an editor

Have you ever written an editor? I am going to show you how to write an editor which will work without recompiling on Windows, Linux, AIX, solaris, and Mac.  An editor which can safely handle unicode encoded languages and is both fast and small. 

Here is your editor.   

# In file named editor.tcl
package require Tk                                     ; # Make sure the Tk library is loaded

catch { console show } str                             ; # Show a console for command input

set rightScrollbar .sb                                 ; # symblic name of scrollbar
set textWin .text                                      ; # symbolc name of text window

scrollbar $rightScrollbar -command "$textWin yview"    ; # create a scrollbar
text $textWin -yscrollc "$rightScrollbar set"          ; # create a text window

pack $rightScrollbar -side right -fill y               ; # put the scrollbar on right
pack $textWin -side right -fill both -expand 1         ; # fill the rest of window with text

proc loadText {w fn} {                                 ; # routine to load text
    if {$fn==""} return                                    ; # check for bad input
    global fileName                                        ; # make a global named fileName
    set fileName $fn                                       ; # save file name for later
    wm title . [file tail $fn]                             ; # set title of window to filename
    set fp [open $fn]                                      ; # open the file
    $w delete 1.0 end                                      ; # delete any current text
    $w insert end [read $fp]                               ; # insert new text
    close $fp                                              ; # close file
}
proc saveText {w fn} {                                 ; # routine to save text
    if {$fn==""} return                                    ; # check for bad input
    set fp [open $fn w]                                    ; # open file     
    puts -nonewline $fp [$w get 1.0 end]                   ; # write to file
    close $fp                                              ; # close file
}

if {$argc > 0} {                                       ; # if started with filename
    loadText $textWin [lindex $argv 0]                     ; # load file
} else {
}
focus -force $textWin                                  ; # give text window the focus

Now you can edit a file with the command "wish editor.tcl fileToExit.txt".

The language used is Tcl.  Got to ActiveState and follow the directions to download and install for your platform (http://www.activestate.com/activetcl).