Managing Methods and Classes
The 4D code used across your project is written in methods and classes.
The 4D IDE provides you with various features to create, edit, export, or delete your code. You will usually use the included 4D code editor to work with your code. You can also use other editors such as VS Code, for which the 4D-Analyzer extension is available.
Creating methods
A method in 4D is stored in a .4dm file located in the appropriate folder of the /Project/Sources/ folder.
You can create several types of methods:
- All types of methods can be created or opened from the Explorer window (except Object methods which are managed from the Form editor).
- Project methods can also be created or opened from the File menu or toolbar (New/Method... or Open/Method...) or using shortcuts in the Code editor window.
- Triggers can also be created or opened from the Structure editor.
- Form methods can also be created or opened from the Form editor.
Creating classes
User classes
A user class in 4D is defined by a specific method file (.4dm), stored in the /Project/Sources/Classes/ folder. The name of the file is the class name. For example, a class named "Polygon" will be stored in the following file:
Project folder
Project
Sources
Classes
Polygon.4dm
You can create a class file from the File menu or toolbar (New > Class...) or in the Methods page of the Explorer window. You can also use the Ctrl+Shift+Alt+k shortcut.
In the Methods page of the Explorer, classes are grouped in the Classes category.
To create a new class, you can:
- select the Classes category and click on the
button. - select New Class... from the action menu at the bottom of the Explorer window, or from the contexual menu of the Classes group.
- select New > Class... from the contexual menu of the Explorer's Home page.
When naming classes, you should keep in mind the following rules:
- A class name must be compliant with property naming rules.
- Class names are case sensitive.
- Giving the same name to a class and a database table is not recommended, in order to prevent any conflict.
ORDA classes
ORDA data model user classes are high-level class functions created above the data model.
An ORDA data model class is defined by adding, at the same location as regular class files (i.e. in the /Sources/Classes folder of the project folder), a .4dm file with the name of the class. For example, an entity class for the Utilities dataclass will be defined through a UtilitiesEntity.4dm file.
4D automatically pre-creates empty classes in memory for each available data model object.
By default, empty ORDA classes are not displayed in the Explorer. To show them you need to select Show all data classes from the Explorer's options menu:
ORDA user classes have a different icon from regular classes. Empty classes are dimmed:
To create an ORDA class file, you just need to double-click on the corresponding predefined class in the Explorer. 4D creates the class file and add the extends code. For example, for an Entity class:
Class extends Entity
Once a class is defined, its name is no longer dimmed in the Explorer.
To open a defined ORDA class in the 4D Code Editor, select or double-click on an ORDA class name and use Edit... from the contextual menu/options menu of the Explorer window:
For ORDA classes based upon the local datastore (ds), you can directly access the class code from the 4D Structure window:
Support in 4D IDE
In the various 4D windows (code editor, compiler, debugger, runtime explorer), class code is basically handled like a project method with some specificities:
- In the code editor:
- a class cannot be run
- a class function is a code block
- Goto definition on an object member searches for class Function declarations; for example, "$o.f()" will find "Function f".
- Search references on class function declaration searches for the function used as object member; for example, "Function f" will find "$o.f()".
- variables typed as a user or ORDA class automatically benefit from autocompletion features. Example with an Entity class variable:
- In the Runtime explorer and Debugger, class functions are displayed with the
<ClassName>constructor or<ClassName>.<FunctionName>format.
Deleting methods or classes
To delete an existing method or class, you can:
- on your disk, remove the .4dm file from the "Sources" folder,
- in the 4D Explorer, select the method or class and click
or choose Move to Trash from the contextual menu.
To delete an object method, choose Clear Object Method from the Form editor (Object menu or context menu).
Design Object Access commands
You can access the contents and paths of all methods in your applications by programming, thanks to the "Design Object Access" command theme. This source toolkit facilitates the integration into your applications of code control tools and more particularly version control systems (VCS). It also lets you implement advanced systems for code documentation, for building a custom explorer or for organizing scheduled backups of the code saved as disk files.
The following principles are implemented:
- Each method and form in a 4D application has its own address in the form of a pathname. For example, the trigger method for table 1 can be found at "[trigger]/table_1". Each object pathname is unique in an application.
- You can access objects in the 4D application using the commands of the "Design Object Access" command theme, for example
METHOD GET NAMESorMETHOD GET PATHS. - Most of the commands in this theme work in both interpreted and compiled mode. However, commands that modify properties or access contents executable from methods can only be used in interpreted mode (see the table below).
- You can use all the commands of this theme with 4D in local or remote mode. However, keep in mind that you cannot use certain commands in compiled mode: the purpose of this theme is to create custom development support tools. You must not use these commands to dynamically change the functioning of a database that is running. For example, you cannot use
METHOD SET ATTRIBUTEto change a method attribute according to the status of the current user. - When a command of this theme is called from a component, by default it accesses the component objects. In this case, to access objects of the host, you just pass a
*as the last parameter.
Use in compiled mode
For reasons related to the principle of the compilation process, only certain commands in this theme can be used in compiled mode. The following table indicates the available of the commands in compiled mode:
The error -9762 "The command cannot be executed in a compiled database." is generated when the command is executed in compiled mode.
Creation of pathnames
Pathnames generated for 4D objects must be compatible with the file management of the operating system. Characters that are forbidden at the OS level such as ":" are automatically encoded in method names, so that generated files may be integrated automatically in a version control system.
Here are the encoded characters:
| Character | Encoding |
|---|---|
| " | %22 |
| * | %2A |
| / | %2F |
| : | %3A |
| < | %3C |
| > | %3E |
| ? | %3F |
| | | %7C |
| \ | %5C |
| % | %25 |
Examples
Form?1 is encoded Form%3F1
Button/1 is encoded Button%2F1