[GitHub] [maven-site] elharo commented on a diff in pull request #191: docs: system dependencies are not always available

["elharo (via GitHub)" <gi...@apache.org>]

elharo commented on code in PR #191:
URL: https://github.com/apache/maven-site/pull/191#discussion_r1171181009


##########
content/apt/guides/introduction/introduction-to-dependency-mechanism.apt:
##########
@@ -174,9 +174,10 @@ Introduction to the Dependency Mechanism
    unit tests (src/test/java) but not in the model code (src/main/java).
 
  * <<system>>\
-   This scope is similar to <<<provided>>> except that you have to provide the JAR
-   which contains it explicitly. The artifact is always available and is not
-   looked up in a repository.
+   Maven does not add system-scoped dependencies to any classpath.

Review Comment:
   It's been a while but this came up a couple of project ago in my day job, where we spent a lot of effort untangling different kinds of dependency scopes and analyzing dependency graphs. The existing text is wrong in one key respect:
   
   "Dependencies with the scope system are always available and are not looked up in repository." 
   
   However, dependencies with the scope system are *not* "always available". Declaring a dependency such as 
   
   ```
   <dependency>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-site-plugin</artifactId>
             <version>4.0.0-M7</version>
             <scope>system</scope>
   </dependency>
   ```
   
   doesn't magically make it available. This is likely just sloppy writing, and the intent was to document the correct behavior but that's not how the text reads  currently, especially to a dev not steeped in Maven dependency management. 
   
   Let me take another stab at rephrasing this to take into account the points you bring up about non-classpath based resolution of dependencies. 
   



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