[英]How do I use Clojure memfn with a Java constructor?
I want to use a Java constructor as a first-class Clojure function. 我想使用Java构造函数作为一流的Clojure函数。 My use-case is to transform a sequence of strings into a sequence of Java objects that have a constructor with a single string: 我的用例是将一系列字符串转换为一系列Java对象,这些对象具有一个带有单个字符串的构造函数:
Simple Java object: 简单的Java对象:
public class Foo {
public Foo(String aString){
// initialize the Foo object from aString
}
}
And in Clojure I want to do this: 在Clojure中,我想这样做:
(defn make-foo (memfn Foo. a-string))
(apply make-foo '("one" "two" "shoe"))
The apply should return a list of Foo objects created from Strings, but I'm getting this: apply应返回从Strings创建的Foo对象列表,但我得到了这个:
IllegalArgumentException No matching method found: org.apache.hadoop.io.Text. for class java.lang.String clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:53)
Don't bother. 不要打扰。 memfn
is practically deprecated in favor of the anonymous function literal, with which you can also invoke constructors, eg, #(Foo. %)
. memfn
实际上已被弃用,有利于匿名函数文字,您也可以使用它来调用构造函数,例如#(Foo. %)
。
Also, your apply
call is going to try to invoke make-foo
once with three string args. 此外,您的apply
调用将尝试使用三个字符串args调用make-foo
。 You probably instead want: 你可能想要:
(map #(Foo. %) ["one" "two" "three"])
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