将元素附加到 TCL 中的嵌套列表 [英] Append elements to nested list in TCL

问题描述

我想动态地将元素添加到嵌套列表中.考虑以下示例:

I want to dynamically add elements to nested lists. Consider the following example:

set super_list {}
lappend super_list {00 01 02}
lappend super_list {10 11 12}
lappend super_list {20 21}

结果:

super_list = {00 01 02} {10 11 12} {20 21}
[lindex $super_list 0] = {00 01 02}
[lindex $super_list 1] = {10 11 12}
[lindex $super_list 2] = {20 21}

如何将另一个值(例如 22)附加到 [lindex $super_list 2]?

How do I append another value (e.g. 22) to [lindex $super_list 2]?

lappend [lindex $super_list 2] 22

不起作用！

目前我能想到的唯一解决方法是:

The only workaround I could think of so far is:

lset super_list 2 [concat [lindex $super_list 2] {22}]

这真的是唯一的方法吗?

Is this really the only way?

谢谢，莱纳斯

推荐答案

在 Tcl 8.6 中(添加了该功能；它在早期版本中不起作用)您可以使用 lset 来扩展嵌套列表通过索引 end+1:

In Tcl 8.6 (the feature was added; it doesn't work in earlier versions) you can use lset to extend nested lists via the index end+1:

set super_list {{00 01 02} {10 11 12} {20 21}}
lset super_list 2 end+1 22
puts [lindex $super_list 2]
# ==>  20 21 22

你也可以通过使用数字索引来解决最后一个，但我认为 end+1 更容易记忆.

You could address one past the end by using a numeric index too, but I think end+1 is more mnemonic.

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