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https://issues.apache.org/jira/browse/MNG-8015?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17808941#comment-17808941
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ASF GitHub Bot commented on MNG-8015:
-------------------------------------
desruisseaux commented on code in PR #1378:
URL: https://github.com/apache/maven/pull/1378#discussion_r1460555006
##########
api/maven-api-core/src/main/java/org/apache/maven/api/PathType.java:
##########
@@ -0,0 +1,143 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.api;
+
+import java.nio.file.Path;
+import java.util.Objects;
+import java.util.Optional;
+
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.annotations.Nonnull;
+
+/**
+ * The option of a command-line tool where to place the paths to some
dependencies.
+ * A {@code PathType} can identify the Java class-path, the Java module-path,
+ * or another kind of path for another programming language for example.
+ * This class is like an enumeration, except that it is extensible:
+ * plugins can define their own kinds of path.
+ *
+ * <p>Path types are often exclusive. For example, a dependency should not be
both
+ * on the Java class-path and on the Java module-path.</p>
+ *
+ * @see DependencyProperties#PATH_TYPES
+ * @see
org.apache.maven.api.services.DependencyResolverResult#getDispatchedPaths()
+ *
+ * @since 4.0.0
+ */
+@Experimental
+public abstract class PathType {
Review Comment:
The `JavaPathType` focuses on the standard Java tools. In order to avoid
being opinionated, the current strategy is to take the [Java Development Kit
Version 21 Tool
Specifications](https://docs.oracle.com/en/java/javase/21/docs/specs/man/index.html)
and put all options for all kinds of path in the `JavaPathType` enumeration.
So this is non-arbitrary from a Java standard point of view.
If there is a demand for other popular types of path, I suppose that they
could be added to this enumeration as well. But even if they are not added, all
plugins have the possibility to provide their own `PathType` enumeration if
they want.
The `PathType.option()` method could indeed be controversial. The reason for
this API is because some options are formatted is a special way. Currently,
`--patch-module` is the only example I'm aware of, but more may exist. This
architecture makes possible to handle those special cases in dedicated
`PathType` implementations. The presence of this API in a shared place is
because _Java Development Kit Version 21 Tool Specifications_ uses those
options consistently in all tools as far as I know. For `PathType` defined in
plugins, the plugin has the possibility to provide the right option for the
tool that they target.
Note: `JavaPathType` is currently not the only Java-specific interface in
core. There is also `JavaToolchain`.
> Control the type of path where each dependency can be placed
> ------------------------------------------------------------
>
> Key: MNG-8015
> URL: https://issues.apache.org/jira/browse/MNG-8015
> Project: Maven
> Issue Type: Improvement
> Components: Core
> Affects Versions: 4.0.0-alpha-12
> Reporter: Martin Desruisseaux
> Priority: Major
>
> Make possible to declare where each dependency can be placed: on the
> module-path, class-path, agent path, doclet path, taglet path, annotation
> processing path, _etc._ The proposed improvement consists in adding a new
> {{PATH_TYPES}} property that can be associated to dependencies. The property
> value is an array of {{PathType}}, a new enumeration-like class with values
> such as {{CLASSES}}, {{MODULES}}, {{DOCLET}}, _etc._ Contrarily to real Java
> enumerations, this enumeration-like class is extensible: plugins can add
> their own enumeration values. This is required at least for the
> {{--patch-module}} option, where a new {{PathType}} enumeration value need to
> be created for each module to patch.
> Users can control indirectly the {{PathType}} of a dependency by specifying
> the dependency type. Note that there is no direct mapping between the
> dependency type and where the dependency will be placed, but only an indirect
> mapping caused by the fact that using a dependency type implies implicit
> values of some properties such as classifier, and (with this proposal) path
> types:
> * {{<type>jar</type>}} implies {{PathType.CLASSES}} and {{PathType.MODULES}}.
> * {{<type>modular-jar</type>}} implies {{PathType.MODULES}} only.
> * {{<type>classpath-jar</type>}} implies {{PathType.CLASSES}} only.
> * _etc._
> When a plugin requests the paths of dependencies, the plugin specifies the
> types of path it is interested in. For example, a Java compiler plugin can
> specify that it is interested in {{PathType.CLASSES}} and
> {{PathType.MODULES}}, but not {{PathType.DOCLET}}. If a dependency declared
> that it can be placed on the class-path or the doclet-path, only the
> class-path is left after intersection with plugin's request. This is
> important for the next step.
> If, after all filtering such as above paragraph are applied, a dependency has
> only one {{PathType}} left, then there is no ambiguity and we are done.
> Combined with above-cited dependency types like {{modular-jar}} or
> {{classpath-jar}}, this rule allows users to control where the dependency
> will be placed. But if there are two or more {{PathType}} left after
> filtering, then a choice needs to be done. For example if there are both
> {{PathType.CLASSES}} and {{PathType.MODULES}} (which may happen when
> {{<type>jar</type>}} is used), then an heuristic rule similar to Maven 3 can
> be applied: check if a {{module-info.class}} file or an {{Automatic-Name}}
> manifest attribute is present, and base the decision on that.
> This proposal aims to fix MNG-7855.
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