composite

问题 I have struggled with this design problem for some time. I will do my best to explain what I am trying to do and the various approached that I have seen, what I am trying and why. I work in a scientific computing environment where I deal with the same kinds of objects repeatedly. Imagine a galaxy which contains solar systems, each solar system contains planetary systems and each planetary system contains moons. To this end I think of the situation as a “has a” situation, and thus I have used

问题 I have class A, having methods that update properties of B. So, I need inheritance. class B{ public: int x; }; class A : public B{ public: void update(int y){ x = y; } }; I also want to reach function "update" through class B, so I also need composition. class B{ public: A a; int x; }; class A : public B{ public: void update(int y){ x = y; } }; I want my structure as such, so that I want to track properties of objects-type Bs this way: ... B.a.update(5); int n = B.x; However, I cannot use

问题 Is it OK if I create a composite primary key from 4 columns? Like: PRIMARY KEY(name, slug, type, parent) So there should not be more than one row with the same name, slug, type and parent. Are there too many columns? Will it affect performance? I'm using sqlite btw. 回答1: It's usually recommended to have an ID field that is unique on its own. Comparing INTEGER values is faster than comparing strings, so your composite key will affect performance negatively. Adding a column with the following

问题 I see that Composite pattern and dependency injection means public function __construct(ClassToUseInterface $class) { $this->class = $class } So, what's the difference ? 回答1: The code as presented in your question neither represents dependency-injection, nor does it represent the composite pattern. Your code represents what is known as Dependency inversion. Let's answer your question : One way for your code to truly represent Dependency injection is to call the construct function from code

问题 I have File1.csv, with the columns id,name,age. File2.csv has the columns id,designation. In both the files ID refers to same value and is unique. Sample data File1.csv id name age 101 abc 30 102 def 25 File2.csv id designation 101 manager 102 Assistant manager Spring batch should read the files simultaneously, combine the data and write to DB as below id name age designation 101 abc 30 manager 102 def 25 Assistant manager How to read 2 files simultaneously in spring batch? 回答1: You have to

问题 The references are unidirectional. The table (StoreProduct) for this entity is actually a join table that has these fields: Store_id Product_id ExtraBit So I went with an entity having a compoundID (store_id and product_id) and the ExtraBit is just a string: public class StoreProduct { protected StoreProduct():this(null,null,null){ } public StoreProduct(Store c_Store, Product c_Product, String c_ExtraBit) { Store = c_Store; Product = c_Product; ExtraBit = c_ExtraBit; } public virtual int

问题 I'm working in asp.net with Orckestra CMS (before Composite) and Razor Templates and trying to use Vue framework. All is fine when using {{option.text}} <select class="form-control" id="myExample1"> <option v-for="option in options">{{option.text}}</option> </select> But when I insert v-bind attribute, the page is broken: <select class="form-control" id="myExample1"> <option v-for="option in options" v-bind:value="option.value">{{option.text}}</option> </select> Rendering page fail and show

问题 I am building an SWT application, I have used a ScrolledComposite and a Composite inside that. This has a few more buttons and checkboxes . All this is inside a Composite . Now I tried to put this main composite in the tab. It worked fine but the image flickers a lot even if I don't scroll or resize. If I put this main composite inside a shell, its working perfect without any flicker. Why is this happening? 回答1: Did you set the SWT.DOUBLE_BUFFERED style bit on your Composite? That might fix

问题 Let's imagine I have a collection of nodes that I use for my Renderer class later on. Then I have a Visitor class that can visit node or whole collection. It's simple because my collection of nodes it's simply a wrapper to the std::list with few extra methods. The problem is I'd like to have a tree like structure for nodes(instead of simple list) so a node can have a parent and n children. That would be handy as I'd like to be able to pass to my Renderer a node and render everything "below"

问题 I'm kinda new to nhibernate and i ran into a problem. I have the following tables: Table 1: Table Name: Users, Column 1: ID, Column 2: Name Table 2: Table Name: Missions, Column 1: ID, Column 2: Description Table 3: Table Name: UserToDoMissions, Column 1: UserID, Column 2: MissionID, Column 3: Rank Here is the code: MissionMap: public class MissionMap : ClassMap<Mission> { public const string TableName = "tblMissions"; public const string c_id = "achID"; public const string c_name = "achName"