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TCL TK

TCL TK. Tcl/Tk. C functions can become Tcl commands that are invoked interactively Tk = scriptable, portable user interface Windows, X (Unix), MacOS, MacOS X also found in Python and Perl GUI extensions scripts can send commands to each other. Tcl history.

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TCL TK

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  1. TCL TK

  2. Tcl/Tk • C functions can become Tcl commands that are invoked interactively • Tk = scriptable, portable user interface • Windows, X (Unix), MacOS, MacOS X • also found in Python and Perl GUI extensions • scripts can send commands to each other

  3. Tcl history • Developed in late 1980s by John Ousterhout • first release ~1991 • Tk usable around 1992 • see http://www.tcl.tk/doc/tclHistory.html

  4. high-level scripting language less code than Win32 interpreted execute directly, without compiling or linking extensible commands in Tcl or C embeddable Tcl interpreter callable from C most platforms Unix, Mac, Windows hides UI, system call differences autoloading automatically load libraries free source no royalties Tcl/Tk features

  5. Using Tcl/Tk • Three modes: • tclsh for interactive use $tclsh %set x 7 7 • wish for window programs $ wish % button .b –text “Hello” –command exit % pack .b

  6. Tcl/Tk script files • Script file: #!/usr/local/gnu/bin/wish –f button .b –text "Hello, world!" \ –command exit pack .b

  7. Basic operations • print to screen (puts) puts –nonewline "Hello, world!" puts "!!" • assignment (set) set income 32000 puts "income is $income" (using '$' to get the value of a variable) • mathematical expressions (expr) set a 10.0 expr $a + 5 expr int($a/3)

  8. Some useful commands • unset: destroy a variable unset num • info: check whether the named variable has been defined if {![info exists num]} { set num 0 } incr num • window commands wm withdraw . console show

  9. Special characters # : single-line comments, similar to "//" in C \ : escape character, same function as in C : also used to break a long line of code to two lines $ : get the value of a variable • var : name of variable • $var : value of variable [] : evaluate command inside brackets

  10. Control structures • if then else set income 32000 if {$income > 30000} { puts "$income -- high" } elseif {$income > 20000} { puts "$income -- middle" } else { puts "$income -- low" } • while loops set i 0 while {$i < 100} { puts "I am at count $i" incr i }

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