Groovy字符串插值，其值仅在运行时已知 [英] Groovy string interpolation with value only known at runtime

问题描述

我觉得我缺少Groovy处理字符串的方式.我意识到它们是不可变的，但是我想做的是在运行时内插一个值.我不知道怎么办.让我用Python给出一个非常简单的示例(作为可执行伪代码")来说明我的意思.然后，我将给出我在Groovy中尝试过的内容.

I feel like I'm missing something with how Groovy handles strings. I realize that they're immutable, but what I would like to do is interpolate a value at runtime. I can't figure out how. Let me give a really simple example in Python (as "executable pseudo-code") to illustrate what I mean. Then I'll give what I've tried in Groovy.

Python

# string_sample.py 

class MyClass(object):

    greeting = 'Hello, %s!'

    def __init__(self):
        object.__init__(self)

    def sayHello(self, name):
        print self.greeting % name


if __name__ == '__main__':
    m = MyClass()
    m.sayHello('Mario')

上面的照片:你好，马里奥！

时髦

// string_sample.groovy

class MyClass {

    def greeting = "Hello, ${name}!"

    MyClass() {
    }

    void sayHello(name) {
        println greeting
    }
}

m = new MyClass()
m.sayHello('Mario')

上面的Groovy脚本抱怨name是未知的:

The above Groovy script complains that name is unknown:

Caught: groovy.lang.MissingPropertyException: No such property: name for class: MyClass

我了解正在发生的事情以及原因.我只是不确定该怎么办.我意识到可以使用String.format，这还不错:

I understand what's happening and why. I'm just not sure what to do about it. I realize that String.format can be used, which isn't so bad:

    String greeting = "Hello, %s!" 

    // Omitted...

    void sayHello(name) {
        println String.format(greeting, name)
    }

我只是在想，也许有一种 groovier 的方式.有人知道吗谢谢！

I'm just thinking that maybe there's a groovier way of doing it. Anyone know? Thanks!

推荐答案

您可以使用闭包:

class MyClass {

    def greeting = { name -> "Hello, ${name}!" }

    MyClass() {
    }

    void sayHello(name) {
        println greeting(name)
    }
}

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