Solid principles tutorial code#
Is there code for the sake of having code, are things over-engineered? Is the code hard to refactor? Is it one keystroke away from an import loop? Is the code fragile? Does the slightest change ripple through the code base causing untold havoc? Is the code rigid? Does it have a straight jacket of overbearing types and parameters, that making modification difficult? What are some of the properties of bad code that you might pick up on in code review? Now it’s fine to say “that code is ugly” or ”wow that source code is beautiful”, just as you might say “this painting is beautiful” or “this room is beautiful” but these are subjective terms, and I’m looking for objective ways to talk about the properties of good or bad code. If code review is there to catch bad code, then how do you know if the code you’re reviewing is good, or bad? Who here does code review as part of their job?. How many Go programmers are there in the world? Think of a number and hold it in your head, we’ll come back to it at the end of this talk. How many Go programmers are there in the world? This post has been translated to Russian by Artem Zinoviev. This post has been translated into Simplified Chinese by Haohao Tian. We check whether the classes depend on some other classes (instantly instantiate objects of other classes, etc.) and if this relationship takes place, we replace it with a dependence on abstraction.This post is based on the text of my GolangUK keynote delivered on the 18th of August 2016.Ī recording of the talk is available on YouTube. "Dependencies should be built on abstractions, not details" We check how much the interface contains methods and how different functions are superimposed on these methods, and if necessary, we break the interfaces.
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"Many specialized interfaces are better than one universal" The principle of interface separation (Interface segregation).If this happened, then the principle is not observed "Objects in the program can be replaced by their heirs without changing the properties of the program"įor this, we check whether we have strengthened the preconditions and whether the postcondition has weakened. The substitution principle of Liskov substitution."Software entities must be open for expansion, but they are closed for modification"įor this, we represent our class as a "black box" and see if we can change its behavior in this case. To do this, we check how many reasons we have for changing the class-if there is more than one, then we must break this class. "One object must be assigned to each facility" The principle of a single responsibility.Summarizing all of the above, I would like to make the following cheat sheet So now, the Customer class now depends only on the abstraction, and the specific implementation, Return $query -> fetchObject ( "Order" ) $statement -> execute (array( ":id" => $orderID )) $statement = $pdo -> prepare ( "SELECT * FROM `orders` WHERE id=:id" ) Their behavior, we do not need to modify their source code.Ĭonsider the example of OrderRepository class. In more simple words it can be described as - all classes, functions, etc.
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This principle declares that - "software entities should be open for extension, but closed for modification." Now each class is engaged in the specific task and for each class there is only one reason to change it. To solve this problem is the division of the class into 3 classes, each of which will be to Order class itself, which may lead to inoperability. This leads to the case that if we want to make changes to the print job, or storage techniques, we change the ( calculateTotalSum, getItems, getItemsCount, addItem, deleteItem),ĭisplay order ( printOrder, showOrder) and data handeling As you can see, this class performs the operation for 3 different types of tasks: work with every order