TCL中如何在子线程中访问全局函数或者全局变量

set procedure to kk 是打开过程文件

public x,y 定义全局变量，全局有效

private 是在过程中屏蔽public定义的变量，即私有变量，离开过程，就会实效。

local 定义局部变量，作用域只在本过程。

x＝30 是赋值语句，将30赋给x

public x,y &&定义全局变量

set proc to kk &&打薯芦颤开过程哗租文件

x=20 &&全局变量赋值

y=50

do a1 &&执行过程a1

?x,y

set proc to

return

*过程序文件kk.prg

proc a1

private x &&定义私有变量，屏蔽调用过程的x

x=30&&x＝30

local y &&定数败义局部变量，y为逻辑假

do a2 &&执行a2

?x,y

return

proc a2

x="kkk" &&x赋值，x如果脱离a2过程，x变成全局变量，即x＝20

y="mmm" &&y从a1过程出来，变成全局变量，重新赋值“mmm”

return

看着我的解释导顺序，就会明白的

不像c，Tcl的变量在使用前不需要声明。Tcl的变量在它首次被赋值时产生，使用set命令。变量可以用unset命令删除，虽然并不强制需要这样做。

变量的值通过$符号访山友问，也叫变量交换。

Tcl是一个典型的”弱类型定义”语言，这意味者任何类型可以存储在任何变量中。例如，同一个变量可以存储数字，日余嫌期，字符串甚至另一段Tcl script.

Example 1.1:

set foo john

puts Hi my name is $foo

Output: Hi my name is john

Example 1.2:

set month 2

set day 3

set year 97

set date $month:$day:$year

puts $date

Output: 2:3:97

Example 1.3:

set foo puts hi

eval $foo

Output: hi

在这个例子里，变量foo存储了另竖唯手外一段Tcl script.

表达式

包括数学表达式，关系表达式，通常用 expr命令。

Example 2.1:

expr 0 == 1

Output: 0

Example 2.2:

expr 1 == 1

Output: 1

两数比较，true则输出1，false输出0

Example 2.3:

expr 4 + 5

Output: 9

Example 2.4:

expr sin(2)

Output: 0.909297

命令传递

以运算结果替代Tcl命令中的部分

Example 3.1:

puts I am [expr 10 * 2] years old, and my I.Q. is [expr 100 - 25]

Output: I am 20 years old, and my I.Q. is 75

方括号是命令传递的标志

Example 3.2:

set my_height 6.0

puts If I was 2 inches taller, I would be [expr $my_height + (2.0 / 12.0)] feet tall

Output: If I was 2 inches taller, I would be 6.16667 feet tall

命令流控制

Tcl有判断流转(if-elseswitch)和循环控制(whileforforeach)

Example 4.1:

set my_planet earth

if {$my_planet == earth} {

puts I feel right at home.

} elseif {$my_planet == venus} {

puts This is not my home.

} else {

puts I am neither from Earth, nor from Venus.

}

set temp 95

if {$temp <80} {

puts It's a little chilly.

} else {

puts Warm enough for me.

}

Output:

I feel right at home.

Warm enough for me.

Example 4.2:

set num_legs 4

switch $num_legs {

2 {puts It could be a human.}

4 {puts It could be a cow.}

6 {puts It could be an ant.}

8 {puts It could be a spider.}

default {puts It could be anything.}

}

Output:

It could be a cow.

Example 4.3:

for {set i 0} {$i <10} {incr i 1} {

puts In the for loop, and i == $i

}

Output:

In the for loop, and i == 0

In the for loop, and i == 1

In the for loop, and i == 2

In the for loop, and i == 3

In the for loop, and i == 4

In the for loop, and i == 5

In the for loop, and i == 6

In the for loop, and i == 7

In the for loop, and i == 8

In the for loop, and i == 9

Example 4.4:

set i 0

while {$i <10} {

puts In the while loop, and i == $i

incr i 1

}

Output:

In the while loop, and i == 0

In the while loop, and i == 1

In the while loop, and i == 2

In the while loop, and i == 3

In the while loop, and i == 4

In the while loop, and i == 5

In the while loop, and i == 6

In the while loop, and i == 7

In the while loop, and i == 8

In the while loop, and i == 9

Example 4.5:

foreach vowel {a e i o u} {

puts $vowel is a vowel

}

Output:

a is a vowel

e is a vowel

i is a vowel

o is a vowel

u is a vowel

Procedures

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