3

我似乎无法弄清楚如何将'when'关键字添加到应该表现为'if'的BOO 。我想我可以制定一个方法，但是我不能像使用 if 那样移动 when 。任何指针将不胜感激。

-标记

4

2 回答 2

11

这会做你想要的：

import Boo.Lang.Compiler.Ast
import Boo.Lang.Compiler.MetaProgramming

macro when:
    return [|
        if $(when.Arguments[0]):
            $(when.Block)
    |]

x = 1
when x == 1:
    print "x equals one"
when x == 2:
    print "x equals two"

顺便说一句，请随时（也）在 Boo 邮件列表上询问以更快地获得（更多）答案；）

http://groups.google.com/group/boolang/

于 2009-01-19T08:40:24.653 回答
0

This would be a job for a macro. From the page you linked to, it seems that Boo has syntactic macros.

As an aside note, why do you need an exact duplicate of an existing functionality?

于 2009-01-16T01:53:14.397 回答