什么是间接宾语符号，为什么不好，以及如何避免它? [英] What is indirect object notation, why is it bad, and how does one avoid it?

问题描述

标题几乎概括了它，但无论如何这里是长版本.

The title pretty much sums it up, but here's the long version anyway.

在发布一小段 perl 代码后，有人告诉我避免使用间接对象表示法，因为它有几个副作用".评论引用了这一行:

After posting a small snippet of perl code, I was told to avoid indirect object notation, "as it has several side effects". The comment referenced this particular line:

my $some_object = new Some::Module(FIELD => 'value');

因为我一直都是这样做的，所以为了与时俱进，我问:

As this is how I've always done it, in an effort to get with the times I therefore ask:

• 这有什么不好?(具体)
• 潜在的(可能是负面的)副作用是什么?
• 该行应该如何重写?

我正要问评论者，但对我来说，这值得自己发帖.

I was about to ask the commenter, but to me this is worthy of its own post.

推荐答案

主要问题是它的歧义.是否

The main problem is that it's ambiguous. Does

my $some_object = new Some::Module(FIELD => 'value');

是指调用Some::Module包中的new方法，还是调用当前包中的new函数用给定的参数调用Some包中的Module函数的结果?

mean to call the new method in the Some::Module package, or does it mean to call the new function in the current package with the result of calling the Module function in the Some package with the given parameters?

即，它可以被解析为:

# method call
my $some_object = Some::Module->new(FIELD => 'value');
# or function call
my $some_object = new(Some::Module(FIELD => 'value'));

另一种方法是使用显式方法调用符号Some::Module->new(...).

The alternative is to use the explicit method call notation Some::Module->new(...).

通常，解析器会正确猜测，但最佳做法是避免歧义.

Normally, the parser guesses correctly, but the best practice is to avoid the ambiguity.

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