Changes for page Functions

Last modified by chrisby on 2024/01/13 18:39

From version 1.9
edited by chrisby
on 2023/11/18 23:20
Change comment: There is no comment for this version
To version 1.11
edited by chrisby
on 2023/12/06 09:08
Change comment: There is no comment for this version

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3 3  * **Functions should be small.** Maximum 20 lines. Blocks and indentation should also be short. Blocks inside if, else, or while statements should be one line. A function call should probably be included. Indentation depths should be no more than one or two levels.
4 4  * **Functions should do only one task.** They should do its task well. They should do only that task. All instructions within the function should be on the same abstraction level. Sub-functions perform tasks which are one abstraction-level deeper. Sections within a function are symptoms that it performs more than one task. These function should be decomposed.
5 5  * **One abstraction level per function.** The 'stepdown rule' states that code should be easy to read from top to bottom: Under a function, its subfunctions should go down one level of abstraction.
6 -* S**eparate statement and query.** Functions should either provide information about an object or do something with an object, but not both.
6 +* The flow of reading should follow the flow of control. [[Here|doc:.Function Ordering Example.WebHome]] is an example.
7 +* **Separate statement and query.** Functions should either provide information about an object or do something with an object, but not both.
7 7  * **Exceptions are better than error codes** (with if/else statements).
8 8   * Error.java is a dependency magnet with its enumeration of error codes and should be replaced by exceptions and derivatives of the Exception class, which allows easy extensibility in accordance with the Open-Closed Principle.
9 9   * Extract try/catch blocks. Error processing is a task. So it deserves its own function.