红宝石句法糖:处理零食 [英] ruby syntactic sugar: dealing with nils

问题描述

可能已经问过了，但我找不到它..这是2种常见的情况(对我来说是在编程rails ..时)，这令人沮丧地用ruby编写:

probably asked already but I couldn't find it.. here are 2 common situation (for me while programming rails..) that are frustrating to write in ruby:

"a string".match(/abc(.+)abc/)[1]

在这种情况下，由于字符串不匹配，我得到一个错误，因此[]运算符在nil时被调用.我想找到的是以下更好的替代方法:

in this case I get an error because the string doesn't match, therefore the [] operator is called upon nil. What I'd like to find is a nicer alternative to the following:

temp="a string".match(/abc(.+)abc/); temp.nil? ? nil : temp[1]

简而言之，如果不匹配，只需返回nil即可，没有错误

in brief, if it didn't match simply return nil without the error

第二种情况是这种情况:

The second situation is this one:

var = something.very.long.and.tedious.to.write
var = something.other if var.nil?

在这种情况下，我只想为var分配一些东西，如果它不是nil，我要分配一些东西.other..

In this case I want to assign something to var only if it's not nil, in case it's nil I'll assign something.other..

有什么建议吗?谢谢！

推荐答案

首先，我建议 ick 的也许(相当于 and )

For the first I'd recommend ick's maybe (equivalent to andand)

"a string".match(/abc(.+)abc/).maybe[1]

我不确定我是否理解第二个，你想要这个吗?

I am not sure I understand the second one, you want this?

var = something.very.long.and.tedious.to.write || something.other

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