CODEWITHSUNDEEP
oopdesign-patterns
Alex Aparin
Alex Aparin

Reputation: 4522

Which design pattern allows to perform deferred updating of an object?

I have some hierarchy of classes. I want to implement deferred updating of any instance from this hierarchy. In other words, we should update an object in the only case where we will use any public method of the object. What is the best design pattern which allows to implement such a behaviour?

Here is a simple example of a such case:

I have a complex model, which cannot update a view (in performance purposes). Therefore the view should automatically update itself during access to any of its public methods.

Upvotes: 0

Views: 475

Answers (4)

Ishika Mishra
Ishika Mishra

Reputation: 129

Proxy design pattern is used . It controls access to original object allowing you to perform either before or after request goes to original object. For more information you can refer this link below https://refactoring.guru/design-patterns/proxy

Upvotes: 1

dm03514
dm03514

Reputation: 55972

Model-view-viewmodel (MVVM) relates to what vz0 posted.

In this pattern the view observers the view model, and updates itself accordingly, allowing you to decouple the GUI from the data representation.

Upvotes: 0

jaco0646
jaco0646

Reputation: 17104

I am interpreting the phrase deferred updating to mean lazy loading. In that case, it sounds like you're describing the proxy pattern. A proxy is used to control access to another object or resource, and the first reason mentioned by the GoF book for controlling access to an object is,

...to defer the full cost of its creation and initialization until we actually need to use it.

In other words, you can update an object only when one of its public methods is actually called.

Upvotes: 2

vz0
vz0

Reputation: 32923

Design patters are rarely used for performance purposes. On the contrary, you break a pattern to get better performance.

To listen for a change in the model you use Observer.

To do some action when a method is invoked, you use a Proxy.

Upvotes: 2

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