Java的toString（）对Clojure函数的等式 [英] Equivilent of Java's toString() for Clojure functions

问题描述

一些Java代码我使用在我的Clojure函数对象上调用 toString（），它返回类似＃< ns $ something something .something $ something @ 7ce1eae7>> - 我想返回别的东西...可能有一种方法来在函数中包含一些元数据，所以他们的对象的 toString（）

some Java code I'm using invokes toString() on my Clojure function objects, which return something like #<ns$something something.something$something@7ce1eae7>>- I want to return something else...presumably there's a way to include some metadata in the functions so their objects' toString() returns that instead ?

推荐答案

如果你只想打印出对象的REPL更有意义的是，您可以为有问题的类实现 defmethod print-method 。

If you just want to make the REPL print-out of your objects more meaningful, you can implement a defmethod print-method for the class in question.

我最近写的一些代码;这使得Selenium-WebDriver WebDriver对象的REPL打印更有意义：

Here's a shortened version of some code I've written recently; this makes the REPL print-out of a Selenium-WebDriver WebDriver object more meaningful:

(defmethod print-method WebDriver
[o w]
(print-simple
 (str "#<" "Title: "    (.getTitle o) ", "
           "URL: "      (.getCurrentUrl o) " >")
  w))

; Title：A Title，URL： http://example.com >

This prints out like #<Title: A Title, URL: http://example.com >

这里， WebDriver 代表一个类;你可以通过为适当的类实现 print-method ，为内置的Clojure数据结构轻松做到这一点（The Joy of Clojure features a print -method for clojure.lang.PersistentQueue ，它在默认情况下没有很好的表示）。上面的 o 是你正在处理的实际对象， w 是一个writer函数）。

Here, WebDriver represents a class; you can just as easily do this for built-in Clojure data structures by implementing print-method for the appropriate class (The Joy of Clojure features a print-method for clojure.lang.PersistentQueue which has no nice representation by default). The o above is the actual object you're dealing with and w is a writer (required by these kinds of print functions).

这篇关于Java的toString（）对Clojure函数的等式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！