16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
74 lines
2.3 KiB
Plaintext
74 lines
2.3 KiB
Plaintext
== Why is this an issue?
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According to its JavaDocs, the intermediate Stream operation ``++java.util.Stream.peek()++`` “exists mainly to support debugging” purposes.
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A key difference with other intermediate Stream operations is that the Stream implementation is free to skip calls to ``++peek()++`` for optimization purpose. This can lead to ``++peek()++`` being unexpectedly called only for some or none of the elements in the Stream.
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As a consequence, relying on ``++peek()++`` without careful consideration can lead to error-prone code.
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This rule raises an issue for each use of peek() to be sure that it is challenged and validated by the team to be meant for production debugging/logging purposes.
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=== Noncompliant code example
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[source,java]
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----
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Stream.of("one", "two", "three", "four")
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.filter(e -> e.length() > 3)
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.peek(e -> System.out.println("Filtered value: " + e)); // Noncompliant
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----
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=== Compliant solution
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[source,java]
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----
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Stream.of("one", "two", "three", "four")
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.filter(e -> e.length() > 3)
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.foreach(e -> System.out.println("Filtered value: " + e));
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----
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== Resources
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* https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#peek-java.util.function.Consumer-[Java 8 API Documentation]
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* 4comprehension: https://4comprehension.com/idiomatic-peeking/[Idiomatic Peeking with Java Stream API]
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* Data Geekery: https://blog.jooq.org/2014/06/13/java-8-friday-10-subtle-mistakes-when-using-the-streams-api/[10 Subtle Mistakes When Using the Streams API]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Challenge this use of "Stream.peek".
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=== Highlighting
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The "Stream.peek" invocation
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'''
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== Comments And Links
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(visible only on this page)
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=== on 4 Jan 2021, 17:52:38 Sebastien Lesaint wrote:
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Hi,
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I got a notification of a change on this ticket and reread the description.
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This made me realize that the example is misleading in the same way the description text was: it's focused on the missing terminal operation, which is the scope of https://rules.sonarsource.com/java/RSPEC-3958, not of this rule.
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I don't have an example to suggest, nothing obvious comes to my mind. Which leads me to wonder whether the difficulty of finding an example could be a smell of the rule being a bit fragile...
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endif::env-github,rspecator-view[]
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