Tcl語法介紹

Tcl Programming CyberDaemons

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Agenda •Tcl簡介 •變數和運算 •列(List)的操作 •陣列和陣列操作 •物件

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TCL語言 • Tcl 是“工具控制語言（Tool Control Language）＂ 的縮寫。Tk是 Tcl“圖形工具箱＂的擴展(Extension) ，它提供各種標準的 GUI 介面項。Tcl 是一個高階的 電腦語言，語法類似 shell script 與 C 語言之間。 而 tk 是一個使用者界面發展工具，有buttons、 menus、listboxes、 scrollbars 等等。 • Tcl是屬於直譯式的程式語言，就像早期的 Basic 一 樣，所以在寫好 Tcl Script 後需要一個 Tcl 直譯程 式執行您的 Tcl Script 。 而 Tcl 的直譯器叫做 tclsh。 • Tcl 是以可擴展(Extension)性、短的學習曲線和易於 嵌入為特定目標而設計的。

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Tcl 歷史 •John K. Ousterhout於 1988 年開始開發 Tcl/Tk，有好的代碼可重用性，又要簡單易學。 •Tk 的開發始於 1989 年，第一個版本於 1991 年問世。提供一個互動式介面 。 •Tk usable around 1992 •see http://www.tcl.tk/doc/tclHistory.html

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Tcl 特點 • high-level scripting language

• most platforms – Unix, Mac, Windows – hides UI, system call differences

– less code than Motif or Win32

• interpreted

• autoloading

– execute directly, without compiling or linking

• extensible

– automatically load libraries

• free

– commands in Tcl or C

– source – no royalties

• embeddable – Tcl interpreter callable from C Tango Training

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Tcl結構

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如何使用tcl •方式一：tclsh的互動模式 $ tclsh % set x 7 7

•方式二：wish的視窗模式 $ wish % button .b –text “Hello” –command exit % pack .b

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如何使用tcl •方式三：C語言的程式開發 #include main(int argc, char *argv[]) { Tcl_interp *interp = Tcl_CreateInterp(); code = Tcl_EvalFile(interp, argv[1]); if (*interp->result != 0) { printf(“%s\n”, interp->result); } } Tango Training

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簡單的TCL程式 •hello.tcl: set s "Hello World" puts $s –Command: $tclsh hello.tcl –Result: 也可以先進入tclsh (直接下tclsh命令) Hello World

再一行一行鍵入程式 or 下 “tcl 檔名” 命今也可以

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Tcl 語法 •Everything is a list of words – no fixed grammar –first word is command

•{} delay evaluation, may nest •"" only needed when spaces: – set x "foo" = set x foo

•everything can be done dynamically: new procedures, variables, name spaces, ... •interpreter model, but internally compiled into bytecode Tango Training

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變數(variable)的宣告 •利用set來指定變數值。 –Ex.: set a 101

•unset取消此變數 –Ex.: unset a

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變數替換(variable substituion) • 變數替換 – variable substitution: set a 17 – command substitution, evaluated as separate script: set b [expr $a*4] – backslash substitution: set x \$a

• 範例

指令

結果

set b 18 set a [expr $b+2] set a "b-3 is [expr $b-3]"

18 20 b-3 is 15

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變數功能 • incr increments variable •append adds strings to end: append msg "more text" • argv variable is list of command line arguments • env is list of environment variables

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表示式(Math expressions) • 最常使用的是expr • 語法: – expr arg ?arg arg ...?

• 範例: if {$x == $y} { ...} set x [expr {$x + 7}] set y [expr {log($y)}]

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[]代表一個 完整指令

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表示式練習 指令 set b 5 expr ($b*4) - 3 expr $b <= 2 expr $a * cos(2*$b) expr {$b * [fac 4]}

結果 5 17 0 -5.03443 120

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incr指令 • 語法: – incr varName ?increment?

• 作用: – 作加法運算 – Ex.: set i 0 incr i incr i 4 – Result: 0 1 5

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append指令 • 語法: – append varName ?value value value ...?

• 作用: – 在變數後面附加資料 – Ex.: set i 1 append i 2 3 4 5 – Result: 12345

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exec指令 •語法: –exec ?switches? arg ?arg ...?

•作用: –執行外部程式 –Ex.: exec umane –Result: Linux

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字串 „Tcl 對於字串有更多的處理能力 指令 結果 set a Bill Bill expr {$a < "Anne"} 0 expr {$a < "Mary"} 1

„<, >, <=, >=, ==, and != work on strings „Beware when strings can look like numbers

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字串處理 •字串處理的相關指令 regexp regsub

format split scan join

string

„string subcommands compare match trimleft

first last index length range toupper tolower trim trimright

„Note: all indexes start with 0. end means last char

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練習時間 把講義的前面內容，在主機上練習一 遍

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Tcl串列(Tcl lists) • list = ordered collection of elements • separated by spaces or tabs • any proper list can also be a Tcl command! • concat list list – concatenate lists concat {a b c} {d e f}  a b c d e f

• join list sep – convert to string with separator join {a b c} ", "  a, b, c • lappend var element element – append to end of list

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Tcl list manipulation • lindex list index lindex {a b c} 1  b

• linsert list index value value linsert {a b c} 0 A {B C}  A {B C} a b c

• list value value list {a b c} {d e} f  {a b c} {d e} f • llength list llength {a b c}  3 • lrange list first last lrange {a b c} 1 end  b c

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Tcl lists manipulation • lreplace list first list value ... • lsearch ?-glob|-regexp? list pattern • lsort ?-command c? –increasing|decreasing list

lsort –decreasing {a b c}  c b a

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list指令 •語法: –list ?arg arg ...?

•作用: –建立清單 –Ex.: list a b " c d" –Result: a b { c d}

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eval指令 •語法: –eval arg ?arg ...?

•作用: –將參數當成script, 用遞迴方式執行 –Ex.: eval [list set i] 3 –Result: 3

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lindex指令 • 語法: – lindex $list ?index...?

• 作用: – 在list中抽出索引指定的資料 – Ex.: lindex {a b c d e} 2 lindex {a b c d e} end – Result: c e

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linsert指令 • 語法: – linsert $list index element ?element element ...?

• 作用: – 在指定的位置插入資料 – Ex.: set aa [list a b c d e f] linsert $aa end-3 1 2 3 – Result: a b c 1 2 3 d e f

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lappend指令 • 語法: – lappend varName ?value value value ...?

• 作用: – 在變數值後將引數當list附加資料 – Ex.: set var a lappend var b c d – Result: a b c d

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concat指令 •語法: –concat ?arg arg ...?

•作用: –將多個list合併 –Ex.: set a [concat "a b" 1 2 {c {d e}}] lindex $a 5 –Result: d e

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llength指令 •語法: –llength $list

•作用: –計算出list元素的個數 –Ex.: llength {a b} –Result: 2

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lrange指令 •語法: –lrange $list first last

•作用: –在list中將索引範圍內的元素列出 –Ex.: lrange {a b c d} 1 end –Result: b c d

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練習時間 上機操作 30 分鐘

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Tcl陣列(Tcl Arrays) •語法: –array option arrayname ?arg1 arg2 …?

•設定陣列的元素: set myarray(00) 365 puts $myarray(00) –Result: 365

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option: set指令 •語法: –array set arrayname $list

•作用: 一定要偶 –設定陣列元素 數個才行 –Ex.: array set myarray {0 123 00 456 a b} –Result: 0 123 00 456 a b

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option: get指令 • 語法: – array get arrayname index

• 作用: – 回傳一組含陣列索引和值的陣列元素。 – Ex.: array set myarray {0 123 00 456 a b} array get myarray a array get myarray – Result： a b 0 123 00 456 a b

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option: exists指令 •語法: –array exists arrayname

•作用: –若此array存在，則回傳1，否則為0。 –Ex.: array set myarray {0 123 00 456 a b} array exists myarray –Result: 1

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option: names指令 • 語法: – array names arrayname

• 作法: – 回傳陣列索引名稱清單 – Ex.: array set myarray {0 123 00 456 a b} array names myarray – Result: 0 00 a

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option: size指令 •語法: –array size arrayname

•作用: •回傳陣列大小 –Ex.: array set myarray {0 123 00 456 a b} array size myarray –Result: 3

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option: unset指令 • 語法: – array unset arrayname ?pattern?

• 作用: – 將符合pattern的索引拿掉。 – Ex.: array set myarray {0 123 00 456 a b} array unset myarray 0 array name myarray – Result： 00 a

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休息時間 下一階段要介紹流程控制

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TCL之流程控制 •If-else •Switch •For loop •Foreach loop •While loop

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if-then-else •命令的語法為： if expression ?then? body1 ?else? ?body2?

if expr1 ?then? body1 ?elseif? expr2 ?then? body2…..?elseif? exprN ?else? bodyN

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流程控制範例(if-else) 一定要空一格 其它也一定要

• Ex.:

set grade 90 if {$grade >= 90} { puts "Your level is A！" } elseif {$grade < 90} { puts "Your level isn’t A！" } else { puts "You set wrong data！" }

• Result: Your level is A！

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switch •語法： switch ?option? string pattern body ?pattern body…. switch ?option? string {pattern body ?pattern body…}

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流程控制範例(switch) •Ex.: set num 1 switch $num { 1 {puts "I’m 2 {puts "I’m 3 {puts "I’m default {puts }

David."} Terry."} Ruby."} "What’s your name?"}

•Result: I’m David.

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While Loop •語法： while booleanExpr body

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流程控制範例(while loop) •計算1+2+…+100 –Ex.: set a 0 set ans 0 while {$a < 101} { set ans [expr $ans+$a] incr a 1 } puts $ans –Result: 5050 Tango Training

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Foreach loop •語法： foreach loopVar valueList commandBody

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流程控制範例(foreach loop) •計算1+2+…+10 –Ex.: Set j 0 foreach i {1 2 3 4 5 6 7 8 9 10} { set j [expr $i+$j] } puts $j –Result: 55

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For loop •語法： for initial test final body

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流程控制範例(for loop) •計算1+2+…+100 –Ex.: set ans 0 for {set a 0} {$a < 101} {incr a 1} { set ans [expr $ans+$a] } puts $ans –Result: 5050

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練習時間 各種流程控制的方式都要上機操作!

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Tcl程序(Tcl procedures) •基本語法為： proc 程序名稱 {參數1 參數2…} { 主體Body }

•Procedures behave just like built-in commands: –sub1 3

=> 2

•Arguments can have default values: proc decr {x {y 1}} { expr $x-$y } Tango Training

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程序範例 • procedures can be created dynamically proc power {base p} { set result 1 while {$p > 0} { set result [expr $result * $base] set p [expr $p-1] } return $result }

• 執行 power 2 6

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正規表達式Regular expressions •Tcl提供了兩個用於正規表達式的命令regexp 和regsub。 •這裡的正規表達式實際上是擴展的正規表達式， 與egrep相一致。 •支持^$.+?\>\<()|[]

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Regexp命令 • 語法 regexp ?switches? exp string ?matchVar? ?subMatchVar subMatchVar ...?

•範例：計算數字 regexp -all {[0-7]} "I like 7-Up"

=>returns 1 •範例：檢查字串 regexp T(cl|k) "I mention Tk" w t => returns 1 (match), w becomes "Tk", t gets "k" Tango Training

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正規表達式 . (period) ^ $ \x [chars] (regexp) * + ? |

matches any character matches start of a string matches end of a string single character escape matches any of chars. ^: not. -: range. matches the regexp matches 0 or more of the preceding matches 1 or more of the preceding matches 0 or 1 of the preceding can be used to divide alternatives. Tango Training

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例外處理 •catch用於阻止由於錯誤而導致中斷執行。 •執行catch,每次都返回TCL_OK,無論是否有錯 誤發生。 如有錯誤發生返回1，反之返回0 。 „Can intercept errors (like exception handling): catch {expr {2 +}} msg 1 (catch returns 0=OK, 1=err, other values...) puts msg syntax error in expression "2 +"....

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檔案處理(File I/O) „Tcl file I/O commands: open close fblocked eof

gets seek flush read tell cd fileevent puts pwd filename

glob fconfigure source

„File commands use 'tokens' to refer to files set f [open "myfile.txt" "r"] => file1 (按實際情況會有不同) puts $f "Write this text into file" close $f Tango Training

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檔案處理 „gets and puts are line oriented set x [gets $f] reads one line of $f into x „範例 set f [open /etc/passwd r] => file2 (按實際情況會有不同) gets $f => root:x:0:0:root:/root:/bin/bash

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檔案處理 „read can read specific numbers of bytes read $f 100 => (up to 100 bytes of file $f) „seek, tell, and read can do random-access I/O set f [open "database" "r"] seek $f 1024 read $f 100 => (bytes 1024-1123 of file $f)

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info指令 „what variables are there? –info vars, info globals, info locals, info exists

„what procedures have I defined, and how? –info procs, info args, info default, info body, info commands

•範例 proc ff {abc} {puts Hello} info args ff =>abc

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練習時間

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