Design Patterns and Software Engineering Techniques for Java, and How They May Apply to Chisel
HOW IT IS DONE IN JAVA Design Patterns and Software Engineering Techniques for Java, and how they may apply to Chisel CS 294-88: Declarative Hardware Design Martin Maas, 03/05/2013 Introduction I Java has been very popular language in production use for a long time (especially enterprise applications). I Significant performance overheads (GC, JIT,...), yet people are using it for big, mission-critical applications. I Reason (arguably): Enforces rigorous design methodology; availability of a large set of design patterns and tools. I Many of these should be applicable to Chisel (Scala is fundamentally similar to Java, concepts may carry over). I Much of this will be familiar to you already - this talk is intended to organize the content and create a basis for discussion of how to use these techniques in Chisel. Talk Organization 1. Design Strategies 2. Dependency Injection 3. Testing & Mocking 4. Java Tools Part I: Design Strategies Strategy 1: Use Interfaces whenever feasibly possible I Na¨ıveStrategy: When using a component, refer to it by its class type and create an instance of that class. Foo foo = new Foo(); I Problem #1: What if we suddenly need to use a different implementation (e.g. for testing)? I Aside: Could use inheritance, but this breaks abstraction - ideally, declare all classes that are not specifically designed to be inherited from as final. I Problem #2: What if we have a class that wants to provide multiple functionalities? I For example: Consider some class SignalToImageDSP representing a pipeline stage that takes signal data and produces image data. Strategy 1: Use Interfaces whenever feasibly possible I Use when initializing a pipeline: SignalDSP prevStage= new SignalDSP(); SignalToImageDSP stage= new SignalToImageDSP(prevStage); ImageDSP nextStage= new ImageProc(stage); I Say we decide at some point that we want to use a truncated version of the pipeline, where the image data is approximated without using sensors.
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