OOP内聚/耦合混淆

Question

I have a question regarding the correct way of splitting objects.

Say I have two objects, such as Tool and Technology. A Technology can have multiple Tool objects associated with it, but is it considered low cohesion/tight coupling for a Technology to know directly about a Tool? Is it bad practice to have the Technology object to contain an array of Tool objects or should there be some sort of third class that would tie them together?

Tool
private id;
private title;

Technology
private id;
private title;
private tools;

Could you provide a simple overview of how it would be best to associate the to objects with one another? At first glance it seems like it would be ok to me, but would it really be appropriate for a Technology object to have getter/setter methods for adding Tools?

Answer 1

If Technology needs Tool objects, there's nothing wrong with it keeping them.

If the Tools are relevant to the Technology object state, than it should contain them inside of it.

Relevant possible methods:

public addTool(Tool $tool);
public removeTool(Tool $tool);
public removeToolByIndex($index);
public getToolFromIndex($index);