如何获取Itcl类成员变量的引用？

发布于 2024-11-28 01:39:37 字数 271 浏览 2 评论 0原文

假设我有以下结构：

package require Itcl


itcl::class AAA {

private variable m_list {}

constructor {} {
    fill m_list list
}

}

如何获取 m_list 上的引用以便编写

foreach elem $reference {.......}

考虑到列表确实很大，我不想复制它！

原文

Say I have the following structure:

package require Itcl


itcl::class AAA {

private variable m_list {}

constructor {} {
    fill m_list list
}

}

How to get a reference on the m_list in order to write

foreach elem $reference {.......}

Consider that list is really big and I don't want to copy it!

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画骨成沙 2024-12-05 01:39:37

Tcl 变量使用写时复制语义。您可以安全地传递一个值，为其分配多个变量，而不必担心它占用更多的内存空间。

例如，

set x {some list} ;# there is one copy of the list, one variable pointing at it
set y $x          ;# there is one copy of the list, two variables pointing at it
set z $y          ;# there is one copy of the list, three variables pointing at it
lappend z 123     ;# there are two copies of the list
                  ;# x and y pointing at one
                  ;# z pointing at the other 
                  ;#     which is different from the first via an extra 123 at the end

上面的代码将产生两个巨大的列表，一个包含 x 和任意 y 都指向的原始数据，另一个包含仅 z 指向的额外元素 123。在 lappend 语句之前，只有一份列表副本，并且所有三个变量都指向它。

Tcl variables use copy-on-write semantics. You can safely pass a value around, assigning multiple variables to it, without worrying about it taking up more space in memory.

For example

set x {some list} ;# there is one copy of the list, one variable pointing at it
set y $x          ;# there is one copy of the list, two variables pointing at it
set z $y          ;# there is one copy of the list, three variables pointing at it
lappend z 123     ;# there are two copies of the list
                  ;# x and y pointing at one
                  ;# z pointing at the other 
                  ;#     which is different from the first via an extra 123 at the end

The above code will result in two giant lists, one with the original data that both x any y point at, and one with the extra element of 123 that only z points to. Prior to the lappend statement, there was only one copy of the list and all three variables pointed at it.

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江湖正好 2024-12-05 01:39:37

以下是如何获取类成员的引用：

package require Itcl


itcl::class AAA {

public variable m_var 5

public method getRef {} {

    return [itcl::scope m_var]
}

}


AAA a

puts [a cget -m_var]

set [a getRef] 10

puts [a cget -m_var]

Here is how to get a reference on the member of a class:

package require Itcl


itcl::class AAA {

public variable m_var 5

public method getRef {} {

    return [itcl::scope m_var]
}

}


AAA a

puts [a cget -m_var]

set [a getRef] 10

puts [a cget -m_var]

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