Perl 子程序原型——正确的方法 [英] Perl Subroutine Prototyping -- The correct way to do it

问题描述

我在我的代码中使用了一个名为 debug 的子例程.它基本上可以让我看到发生了什么等.

I have a subroutine called debug I use in my code. It basically allows me to see what's going on, etc.

sub debug {
    my $message      = shift;
    my $messageLevel = shift;

    our $debugLevel;
    $messageLevel = 1 if not defined $messageLevel;
    return if $messageLevel > $debugLevel;
    my $printMessage = "    " x $messageLevel . "DEBUG: $message
";
    print STDERR $printMessage;
    return $printMessage;
}

我想制作原型，所以我可以做这样的事情:

I want to prototype this, so I can do things like this:

debug "Here I am! And the value of foo is $foo";

或

debug "I am in subroutine foo", 3;

同时，我喜欢把子程序定义放在我的程序底部，这样你就不必费力地翻阅代码的 1/2 来找到程序的核心部分.

At the same time, I like putting subroutine definitions at the bottom of my program, so you don't have to wade 1/2 way through the code to find the meat of the program.

我想这样做:

sub debug($;$);  #Prototype debug subroutine

/Here goes the main program code/

sub debug {      #The entire subroutine goes here
   /Here goes the debug subroutine code/
}

但是，我在执行此操作时收到警告:

However, I get a warning when I do this:

Prototype mismatch: sub main::debug ($;$) vs none at foo.pl line 249.

所以，我一直把原型定义放在两个地方.做这样的事情的正确方法是什么?

So, I'm stuck putting the prototype definition in both places. What is the correct way to do something like this?

停下！模块时间.– 克里斯·卢茨

Stop! Module time. – Chris Lutz

一个模块?你的意思是创建一个单独的文件?这增加了一些复杂性，但并没有解决我正在尝试解决的问题:删除此特定子例程周围的括号的需要.

A module? You mean create a separate file? That adds a bit of complication without solving the issue I'm trying to solve: Removing the need for parentheses around this particular subroutine.

我们的 $debugLevel;无论如何都不应该出现在 sub body 中，但我同意 Chris 的观点.– 思南 Ünür 3 小时前

our $debugLevel; should not be in the sub body anyway, but I agree with Chris on this. – Sinan Ünür 3 hours ago

我们的 $debugLevel 在这种情况下不必在那里，但是如果我定义了一个类并且我想在我的类中使用这个子例程进行调试，我需要它.我可以将它作为 ::debug

The our $debugLevel does not have to be there in this case, but if I defined a class and I want to use this subroutine in my class for debugging, I need it. I can put it in my class as ::debug

令人惊讶的是，远比您想了解的有关 Perl 原型的所有内容都多解决这个问题，但我相信你不能避免在两个地方都写原型.

Surprisingly, Far more than everything you ever wanted to know about prototypes in Perl doesn't address this, but I believe you cannot avoid writing the prototype in both places.

我希望有一种简单的方法来避免它.正如埃里克·斯特罗姆 (Eric Strom) 所展示的那样，有一种方法.不幸的是，它比我的 debug 例程要长.

I was hoping for an easy way to avoid it. There is a way as Eric Strom showed. Unfortunately, it's longer than my debug routine.

我曾经使用原型，但我已经养成了不为子例程编写单独声明并在所有调用中使用括号的习惯:debug("I am in subroutine foo", 3);.有人建议原型确实不是一个好主意.TMTOWTDI – 基思·汤普森 3 小时

I used to use prototypes, but I've developed the habit of not writing separate declarations for subroutines and using parentheses on all calls: debug("I am in subroutine foo", 3);. It's been suggested that prototypes really aren't a good idea. TMTOWTDI – Keith Thompson 3 hours

除非我倾向于这样做:

debug (qq(The value of Foo is "$foo"), 3);

阅读时可能不太清楚，打字也很麻烦.每当你把括号加倍时，你就是在自找麻烦.我最不想做的就是调试我的调试语句.

which can be less clear when reading, and can be a pain to type. Whenever you double up parenthese, you're asking for trouble. The last thing I want to do is debug my debug statements.

你为什么需要原型?请参阅此问题如何将可选参数传递给 Perl 函数 – TLP

Why do you want prototypes? See this question How to pass optional parameters to a Perl function – TLP

是的，原型设计有很多问题.主要问题是它根本没有做人们认为它应该做的事情:声明传递给函数的参数的变量类型.

Yes, there are lots of problems with prototyping. The main problem is that it simply doesn't do what people think it should do: Declare the variable types for the parameters you're passing to your function.

这不是我在这里使用原型的原因.

This is not the reason I'm using prototyping here.

我很少使用原型.事实上，这可能是我所有代码中唯一的案例.

I rarely use prototypes. In fact, this is probably the only case in all of my code where I do.

推荐答案

完全摆脱原型:

sub debug;

debug "Here I am! And the value of foo is $foo";
debug "I am in subroutine foo", 3;

sub debug {
    # body of debug
}

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