I have been using code generation for several years, and have seen it be an important key to the success of the projects. Code generation assures a high quality of code as the generated code contains no copy-paste errors or other errors often encountered in manually written code.
Code generation also provides you with a very high maintainability of the code. If you generated code based on a database structure, you only need to "press a button" to have the code again in sync whenever the database structure changes. On the other hand, if you want to perform an architectural change, for instance have all your data objects implement INotifyPropertyChanged in the System.
ComponentModel namespace , you only need to change the generating template, then "press the button" again But for these benefits to come true, you must follow two important rules when using code generation on your project:. This implies that you should avoid 'interactive code generation' where you choose a menu option in your IDE, then enter some data in a form and have a code file generated, or even worse, a piece of code.
Interactive code generation can be a handy addition to your coding toolkit, such as snippets and other IDE features. It increases your typing rate, but not the maintainability of your code. Because of rule 1, you should also never manually modify generated code. Therefore, the generated code must closely match your needs see also rule 2 so that you don't need to change it. You can however generate code that is adaptable and extendable.
For instance, declare the generated methods virtual so you could still create a subclass and override methods, or declare your classes partial - this will allow you to extend them by simply adding an additional, non-generated file. Because of rule 1, the generated code must closely match your needs. You must therefore make sure that all current and future requirements will be supported. A common transgression of this rule is to generate data objects based on database table definitions.
Although database table definitions are a good starting point to generate data objects from, it is not a place where you can indicate which generated property should be made "public" and which should be made "internal". Whenever I would have the requirement to specify the visibility modifiers of the generated properties, I would come into trouble. Good sources for code generation include:.
As an alternative to generation based on database definitions, you could mix database definition data with information stored in 'meta'-tables stored in the database itself. To match the first rule, the generator does not interactively integrate within your IDE.
Instead, it's a command-line tool and all arguments can be stored in a file. This way, you can rerun the code generation on your project with a single command on the command prompt! As of the second rule, simple, the code generator makes no assumption whatsoever about the generation source. So it provides no default source to generate from, and you'll have to create and provide your own source.
Keep in mind that whatever source you choose, it should be a source you have full control over. You must be able to extend the information stored in the source to extend the capabilities of the code generation. This article is not about the making of the code generator. However, the source code can be downloaded on this page, and to enlighten you on the code structure, here is some information about the code generator implementation. At the core of the parser, you'll find an enhanced version of the Mixed Content Parser I presented in another article.
The Resources folder of the Arebis. CodeGenerator project contains templates for the generated code C and VB. This was needed to allow deletion of the generated assembly files. This could have been avoided by setting GenerateInMemory to true on the CompilerParameters passed to the CodeDomProvider used to compile the template, but then it seems the templates would not have the same debugging capabilities.
NET to the generated code, both compile time and runtime errors are reported by means of the original template source line numbers. The referenced Address class could also be defined, for instance with the following XML:.
With "one press of a button", we want to be able to generate class definitions for those XML files. To achieve this, we need to write some templates. The first template that we write will read the XML files and ask another template to generate the classes:. We name this template BuildClasses. This can be found in the Online tab when adding the template, or you can install the template directly from Visual Studio Gallery ahead of time.
This template will generate entity classes that derive from EntityObject and a context that derives from ObjectContext. The DbContext Generator is now the recommended template for new applications. The EntityObject Generator continues to be available to support existing applications. You will need to select the Online tab when adding the template to download it from Visual Studio Gallery.
If you are using Visual Studio or you will need to select the Online tab when adding the template to download it from Visual Studio Gallery. If you just want ObjectContext code generation without needing to edit the template you can revert to EntityObject code generation.
If you are using Visual Studio this template is already installed. If you create a new model in Visual Studio this template is used by default but the. If you want to customize the template you will need to add it to your project. This template will generate Self-Tracking Entity classes and a context that derives from ObjectContext. In an EF application, a context is responsible for tracking changes in the entities.
However, in N-Tier scenarios, the context might not be available on the tier that modifies the entities. Self-tracking entities help you track changes in any tier.
For more information, see Self-Tracking Entities. We no longer recommend using the STE template in new applications, it continues to be available to support existing applications. Visit the disconnected entities article for other options we recommend for N-Tier scenarios. When you open the template, it has pre-programming with basic details.
The template is also available readymade and it is also created manually by user. Now so many programs support template so it is the best solution for preventing to write similar code, again and again, you can save one of them and use it whenever you want so you can't need to format document each and every time or make new just reference the template and start from there. Using a template, you can save time to format your designE. It is a way that generates code from the high-level specification which is named as template.
In model-driven engineering, template-based code generation is the popular technique it gives both emphasis and automation and the TBCG technique is a good guide for developers in their choice and ideas. The structure of code generators has two inputs: first is template files second is data source for filling out the templates.
That is the combination of two programs - the template code that provides the skeleton or structure of the generated code, and the embedded code that controls how the template is expanded. Template base generated code is like built-in dynamic code. The data source provides information to generate a customized code. This could be unspecified, depending on the embedded code, or it could be a structure that is populated from database metadata table and procedure definitions.
The difficulty of writing large software systems has responsible to an increased interest in generative programming where one program creates another program. The generator generates code using the abstract data model and Template-based code generation TBCG uses templates to describe the structure of the target text. Separation of model and template. The template is strongly separated from the template control logic that is referred by the code generator in a consistent and predictable manner.
Again, and again using the templates is like as the meta-data models are as easy as associating the relevant templates and meta-data sources. Clarity and Conciseness. They merely represent an abstract description of their target code and thus don't require the template developer to understand any additional language.
Standard Control Code Inference.
0コメント