Objects 101 - Everything and Objects with Eric Hosick


Uploaded by EricHosick on 23.05.2010

Transcript:
Ok, so let's talk about objects.
What is an object?
I know it is a bit of a cliché, but this apple is an object.
We can also call it an element or an entity.
And depending on the profession that you choose...
The definitions might be a little bit different.
But from here on out, we'll just refer to things like this as objects.
So what are the aspects or characteristics of an object?
Well, first of all they have an existence or a conceptual reality.
So, the physical existence of this thing right here... this apple is an object.
But if you were to close your eyes and form a mental picture of that apple in your head...
That mental picture is also an object.
Another characteristic of objects is that they have properties with values or attributes with values.
So this apple right here has maybe the properties of color, shape and weight.
And the values could be... Color could be red/yellow.
Weight could be about 100 grams and the shape would be kinda spherical.
Another interesting aspect is that they are uniquely identifiable.
So if I were to bring up a second apple here... and they look almost the same...
They are actually, in fact, distinguishable (from each other).
Another, uh, aspect of objects is that they’re compose-able.
So I can take... an object and compose it of other objects or I can de-compose it.
I.E. Take an object and break it into its parts.
So, for example, with a car... I could take a chassis, wheels, engine, windows...
Put those together, compose them… and create an object called a car.
I could take that same car and I could break it down into its parts and have, say...
A chassis object, and wheels objects, and windows objects…
And those would be now new objects separate from the original car.
Another aspect of objects is that they can interact, effect and use each other.
So, for example, if I am walking…
I can say that my legs are interacting with the road.
And I am able to move.
Now this creates an interesting characteristic of objects.
Because they end up having a thing called behavior.
And the behavior itself is emergent from the fact objects interact with each other.
So, an example would be a person walking is a behavior.
And…
They are so connected together that if you were to try to imagine walking…
Without legs or without some way of moving…
You really can’t do it.
That’s how connected together interaction is with objects.
And how connected behavior is with the properties of objects themselves: the characteristics.
So finally, I should mention.
That objects really don’t have a usage or a purpose.
Consider an apple for example.
An apple could be eaten…
Or it could be used to grow a tree.
So, its purpose isn’t really there until you use it.
And that actually is the case when it is used in a system.
So, objects actually don’t have purpose until they are used in a system.
And we’ll learn about systems…
In another lecture…