thinkphp Function: D method

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D method

The D method should be used in a more numerous way, to instantiate a custom model class, is a thinkphp framework for the model class instantiation of a package, and implemented a singleton mode, support cross-project and group calls, the invocation format is as follows:
D (' [Project://][Group/] model ', ' model layer name ')
The return value of the method is the instantiated model object.

The D method automatically detects the model class and, if there is a custom model class, instantiates the custom model class, if it does not exist,

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The model base class is instantiated, and the instantiated models are not repeated.
The most common use of the D method is to instantiate a custom model of the current project, for example:

1. Instantiate the user model $User = D (' User ');

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The lib/model/usermodel.class.php file under the current project is imported, and then the Usermodel class is instantiated, so the actual code might be equivalent to the following:

1. Import (' @. Model.usermodel '); $User = new Usermodel ();

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But if you use the D method, if the Usermodel class does not exist, it is automatically called

1. New Model (' User ');

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And the second call without re-instantiation, you can reduce the cost of some object instantiation.

The D method can support cross-grouping and project instantiation models, such as:

1. Instantiate the user model for the Admin Project D (' Admin://user ')//Instantiate the Admin group for user Model D (' Admin/user ')

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Note: To implement a cross-project invocation model, you must ensure that the directory structure of the two projects is tied.

Beginning with version 3.1, the D method can also instantiate other models because of the increased support for the layered model, for example:

1. Instantiate the UserService class $User = D (' User ', ' Service '); Instantiate the Userlogic class $User = D (' User ', ' Logic ');

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1. D (' User ', ' Service ');

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The lib/service/userservice.class.php is imported and instantiated, equivalent to the following code:

1. import (' @. Service.userservice ');
   $User = new Userserivce ();