Lua:嵌套if语句

Question

Lua是一种轻松而强大的语言,但有时感觉缺少一些我们在其他语言中习惯的非常方便的功能.我的问题是关于嵌套if条件.在Perl,Python,C++中,我通常倾向于避免嵌套构造并尽可能编写普通代码,如:

# Perl:
for (my $i = 0; $i < 10; ++$i) {
    next unless some_condition_1();
    next unless some_condition_2();
    next unless some_condition_3();
    ....
    the_core_logic_goes_here();        
}

Lua缺少该语句next或continue语句,因此相同的代码将如下所示:

-- Lua:
for i = 1, 5 do
    if some_condition_1() then
        if some_condition_2() then
            if some_condition_3() then
                the_core_logic_goes_here()
            end
        end
    end
end

所以我想知道是否有标准方法来避免ifLua中的嵌套块？

Answer 1

我不知道这是否特别惯用,但您可以使用单个嵌套循环break来模拟continue

for i = 1, 5 do
    repeat
        if some_condition_1() then break end
        if some_condition_2() then break end
        if some_condition_3() then break end
        the_core_logic_goes_here()
    until true
end

Answer 2

在Lua 5.2上,你可以使用goto语句(请小心)!

该关键字的典型用法之一是替换缺失continue或next语句.

for i = 1, 5 do
  if not some_condition_1() then goto continue end
  if not some_condition_2() then goto continue end
  if not some_condition_3() then goto continue end
  the_core_logic_goes_here()
::continue::
end