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Most modern car radios are much more complex than the one that we will use as an analogy in this module.

The user interface

The radio provides a mechanism (user interface) that allows you to use the data stored therein. When you press one of the station-selector buttons on the front of the radio, the radio automatically tunes itself to the frequency corresponding to that button. (In this case, you, the user, are sending a message to the radio object asking it to perform a particular action.) If you have previously stored a favorite radio station frequency in the storage location corresponding to that button, pressing the button (sending the message) will cause the radio station transmitting at that frequency to be heard through the radio's speakers.

If you have not previously stored a favorite frequency in the storage location corresponding to that button, you will probably only hear static. (That doesn't mean that the radio object failed to respond correctly to the message. It simply means that its response was based on bad data.)

Modifying the stored data

The human interface also makes it possible for you to store or modify those five or more frequency values. This is done in different ways for different radios. On my car radio, the procedure is:

  • Manually tune the radio to the desired frequency
  • Press one of the buttons and hold it down for several seconds.

When the radio beeps, I know that the new frequency value has been stored in a storage location that corresponds to that particular button.

What I have done in this process is to send a message to the radio object asking it to change its state . The beep that I hear could be interpreted as the radio object returning a value back to me indicating that the mission has been accomplished. (Alternately, we might say that the radio object sent a message back to me.)

Responding to a message

We say that an object has changed its state when one or more data values stored in the object have been modified. We also say that when an object responds to a message, it will usually

  • perform an action,
  • change its state,
  • return a value, or
  • some combination of the above.

After following this procedure to program a button, when I press that button (send a message) , the radio object will automatically tune itself to that frequency.

I live in Austin, TX. If I drive to Dallas and press a button that I have associated with a particular radio station in Austin, I will probably hear static. In that case, I may want to change the frequency value associated with that button. I can follow the same procedure described earlier to set the frequency value associated with that button to correspond to one of the radio stations in Dallas. (Again, I would be sending a message to the radio object asking it to change its state.)

Jargon

As you can see from the above discussion, the world of OOP is awash with jargon, and the ability to translate the jargon is essential to an understanding of the published material on OOP. Therefore, as we progress through this series of modules, I will introduce you to some of that jargon and try to help you understand the meaning of the jargon.

Questions & Answers

what is microbiology
Agebe Reply
What is a cell
Odelana Reply
what is cell
Mohammed
how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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