Clojure：协议中没有方法的实现
我正在尝试在 Clojure REPL 中加载 RDF clj-plaza 的 Clojure 库，如下所示
user=> (use 'plaza.rdf.core)
nil
：有一个名为 plaza 的文件夹、一个名为 rdf 的子文件夹和文件 core.clj 可用，据我所知，Clojure REPL 会按应有的方式加载该库。
现在，如果我
user=> (alter-root-rdf-ns “http://www.example.org/”)
"http://www.example.org"
再次这样做，据我所知 core.clj 库正在按其应有的方式报告。 现在，
(def e (document-to-model “http://www.snee.com/rdf/elvisimp.rdf” :xml))
java.lang.IllegalArgumentException: No implementation of method: :load-stream of protocol: #’plaza.rdf.core/RDFModel found for class: nil (NO_SOURCE_FILE:2)
如果我尝试 f.ex，我会得到相同的结果。
(make-triples [["http://triple1" "http://triple2" "http://triple3"]])
源代码中 (core.clj) RDFModel 协议中有一个名为 load-stream 的方法，
(defprotocol RDFModel
"Operations for the manipulation of RDF"
....
(load-stream [model stream format] "Load triples from a stream")
....
并且实现了 load-stream
(defn document-to-model
"Adds a set of triples read from a serialized document into a model"
([stream format]
(load-stream *rdf-model* stream format)))
我似乎无法真正指出这里出了什么问题，在源代码中，这一切似乎都加起来了。
I am trying to load the Clojure library for RDF clj-plaza in Clojure REPL like so:
user=> (use 'plaza.rdf.core)
nil
I have a folder named plaza, and a subfolder named rdf and the file core.clj available and as far as I can tell, Clojure REPL loads the library as it should.
Now, if I do
user=> (alter-root-rdf-ns “http://www.example.org/”)
"http://www.example.org"
And again, as far as I can tell the core.clj library is reporting as it should.
Now I do
(def e (document-to-model “http://www.snee.com/rdf/elvisimp.rdf” :xml))
java.lang.IllegalArgumentException: No implementation of method: :load-stream of protocol: #’plaza.rdf.core/RDFModel found for class: nil (NO_SOURCE_FILE:2)
I get the same result if I try f.ex.
(make-triples [["http://triple1" "http://triple2" "http://triple3"]])
In the source code (core.clj) there is a method called load-stream in the protocol RDFModel
(defprotocol RDFModel
"Operations for the manipulation of RDF"
....
(load-stream [model stream format] "Load triples from a stream")
....
And load-stream is implemented
(defn document-to-model
"Adds a set of triples read from a serialized document into a model"
([stream format]
(load-stream *rdf-model* stream format)))
I can't really seem to pinpoint what is wrong here, in the source code it all seems to add up.
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(defn document-to-model ...)代码段未实现load-stream；它实现了一个名为document-to-model的函数，该函数使用一堆参数调用load-stream，其中第一个参数 -*rdf-model*< /code> —— 需要是 RDFModel 协议已扩展的类型（或者直接实现协议或相应的接口）。clj-plaza在命名空间plaza.rdf.implementations.sesame中提供了RDFModel的两个实现（请参阅(deftype SesameModel .. ., 源代码中的第 218 行）和plaza.rdf.implementations.jena（参见(deftype JenaModel ..., 第 167 行)。需要-ing 它们应该足以引入所述实现；然后您可以将它们与适当类型的*rdf-model*一起使用。The
(defn document-to-model ...)snippet does not implementload-stream; it implements a function calleddocument-to-modelwhich callsload-streamwith a bunch of arguments, the first of which --*rdf-model*-- needs to be of a type to which theRDFModelprotocol has been extended (or which implements the protocol or the corresponding interface directly).clj-plazaprovides two implementations ofRDFModel, in the namespacesplaza.rdf.implementations.sesame(see(deftype SesameModel ..., line 218 in the source) andplaza.rdf.implementations.jena(see(deftype JenaModel ..., line 167).require-ing them should be enough to pull in said implementations; then you can use them with*rdf-model*s of appropriate type.(require... 之后的一步是 (init-jena-framework) 或 (init-sesame-framework)。
one more step after (require... is to (init-jena-framework) or (init-sesame-framework).