《TCL 教程英文版》 笔记 §7 命令分析与置换3：使用[]分组参数

                        §7     命令分析与置换3：使用[]分组参数

            []类似于shell中的反单引号。不过大括号中的[]不执行替换。如果方括号前面有斜杠则不替换。

           

实例：

set x abc

puts "A simple substitution: $x\n"

 

set y [set x "def"]

puts "Remember that set returns the new value of the variable: X: $x Y: $y\n"

 

set z {[set x "This is a string within quotes within braces"]}

puts "Note the curly braces: $z\n"

 

set a "[set x {This is a string within braces within quotes}]"

puts "See how the set is executed: $a"

puts "\$x is: $x\n"

 

set b "\[set y {This is a string within braces within quotes}]"

# Note the \ escapes the bracket, and must be doubled to be a

# literal character in double quotes

puts "Note the \\ escapes the bracket:\n \$b is: $b"

puts "\$y is: $y"

 

执行结果：

A simple substitution: abc

 

Remember that set returns the new value of the variable: X: def Y: def

 

Note the curly braces: [set x "This is a string within quotes within braces"]

 

See how the set is executed: This is a string within braces within quotes

$x is: This is a string within braces within quotes

 

Note the \ escapes the bracket:

 $b is: [set y {This is a string within braces within quotes}]

$y is: def