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Čo PO WEEKNAPPLIGATIOM DEVELOPMENT

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APPLIED INTELLIGENCE

OOP Goes Beyond the Commonsense Meaning of 'Object

to the specific. For example, in designing which sends the same check aekesi
the inventory object shown in the fig- message to all be Mel jp see ža be
ure, the top of the hierarchy might be The ability of objec |

The behaviors for responding to the
This is the sec- message depend on the values of the

| zofe »lar object. a SJE | ch implement it ap-
ond a on ob: AREA a prorainnira tech- the abstract object, "collection." It zj s ze iji s caled Povmoši Risi [tis
za. en len d ligues are used to invoke the behaviors  sponds to a number of messages, such propil he aspects of object-oriented pro
olivno irino object. For example, the verifica- as "add an item" and return an item. Go mia thal strupilfjes complex code.
new technology tion message to an order object would ltisa general-purpose programming To better understand polymorphism,
that's changing invoke an order behavior that would construct that might have been ke let's look'at the inventory object One of
the way pro- send a message to an inventory object predefined in the system or might iz NeREviGes'ehecko ali ventogy (OE
grammers and reguesting the guantity on hand for the Serie se . programmer's library of reus- nore might oda ole IC
A sem Es ime lotne jesta to z The programmer implementing the in- simple to ee a OB Serene? Ke [
VSA NINI ORAL eRE guantity on hand. ventory: object lerarchy might define — Cece MEH TRE VNJ.
of the term "ob- The benefit of this approach is in- categories of parts (such as Type A ho book liko tis PER
ject," we have an  creasingly important as systems get part, Type B part, and so on) as a sub- lie aa
intuitive grasp of large and complex. Programmers imple- class of the collection because the inven: ; ol z ejena
what that menting the order object do not need'to tory is a collection of different types of O HLEVU

check-reorder —> inventory-itemli)
H This has tremendous implications for
NU TIR O mi za! ih za di čb ah kak di bu  NubLaa, program maintainability. As new item
THe Hieratehical AtraHgement of Objects types are pk OE SATE POLA
ject in a progr k ina, Pe Ee EMEA V OR ETEKI new procedures for check orders.
zih oi pra RO ož DI, ana P rope pties, inherited fr ol pirent objec ts, bec olhe | are implemented, the code for the inven-
order form in a business application has nore specifte for edeh šubordihate part. mi MW  tory object never needs to be changed.
properties such as items and guantity o dei This is unlike a conventional application

means. In our everyday world, objects
have both properties and behaviors: An
oven has shape and size; it can bake and
broil.

Ji ke A v KI TAT KIPE - UT NE V mmi that would need to dispatch the correct
re dic a i: n Obleciš Aa uči 8 lu: Gli dali ilels reorder procedure for each inventory
TA Sa ič Mod SRE O resport to messages. z oprana dat Mskaaaki type.
programs can be useh to dasenke MI ba [ Polpeti (<< DRookiventen
environments in which a data-modeling | bbjecis či IMI di Fine-Tuned Inventory Control
language defines objects and relation- | | | hi | | ih | In this example, polymorphism, COU-
ships. In fact, object-oriented technology. ' go oa Mi ia tebi JE pled with both the inheritance of reor- ko
'originated with languages designed for - oi —— — z — zma, — Pi der policies for standard parts and the
simulation and is thriving in graphics KOK VSI umevno rerzvem || ability to customize and override the
applications where the user route Type A IA KA ETA IH EI standard policies for particular parts, al-
objects on the screen. However, the for- Partš | ala He dis. x |

the sere, h lows an organization to program more
al term object: has meaning beyond Heordet border | bide V |. complexity in the reordering logic of a
ne commonsens ] ord. Pl lasi $ | |e rut | | Hi | | uring : icati thus givi
sent physical entities such as inventory nij | | VEGE NEA and a significant competitive advantage.
items, but they can also represent more A number of languages are available
abstract entities such as stacks, num- for programmers interested in experi-
zima lile-browsers, dispatchers or col- menting with object-oriented program-
lections. mi a
ae RS. ming. The oldest and perhaps the purest
zi sei: L contains both data (proper- is Smalltalk, which has some excellent
Les) and procedures (behaviors), a pro- implementations on small machines. The
gramming object can be used to ia om

4 arize" : rammins conceni system enforces object-oriented pro- |
onikjiea Rojude Sbenie K gat i | koorder | MA amming throughout and is an excel:
oje made up of other objects, and oy Ik belev gen tool ea pure object-orient: |

rowsers, which are procedures for ex- ide di gramming. : |
amining files. Mis (di A different approach is to enhance

The properties of an object can't be existing languages with object-oriented
directly accessed from outside the ob- RS mem rea ae O MOLI HEJ: This is the approach taken
ject. They are only manipulated by the peč | o oe by lu and Objective-C, which are
behaviors of the object. The behaviors of both C extenslons, as well as Flavors,

poe Sa only be ebay Bend. ROZA OE Em m nan which is a LISP extension. While thi
mentation of the properties and zs panj program more complexity into the y ofa

Conventional language, it has the disad:
vantage of not forcing the programmer
to use object-oriented technigues consis-

Na vkona of an object is completely hid-. logic of' a manuf' acluring application, giving i
- den from the < The objects dat NI ia A ie nana |
and process a ae EO LANA tuned control and a significant competitive ad

ns Aja, are encapsulated within ite. NIKE The te Rea must unlearn
Poni Sana ea a edi iska | e procedura] pi ogramming style that
zogo kovini pasa s JK zad pilone | Tim ingrained in anyone with pana a |
tan ma zvomer order-entry appli- know anything about the inta, le programmin
cation. The system has an oble šina ines of MA ne about the internal work- items. The inventory items in oh Oto Pp 8 experience. Old pro-

order —which has behaviors that allow ply have to Ritem object. They sim. Bory of parts can themselves be objects, Ta aHing habits are hard to break.

ansra z nee deja w which messages the leh : Peta Next week T'l look at examples of ob- |
manipulation and inspection of its prop-  inventory object wil O AIE such as serew or bolt. The inventory ob- | ject-oriente« rogramming i |
len The definition might look like send nie EI šjte najo and t inherits all the behaviors of the col. — cations. ljam na 8 appli: |

lection object and categ ry
di In addition, object-oriented languages that with oč ni tegory object, so ——
DONE k Zrnec order; property variables: allow information to be organized con. sta ves no further work from the pro- 70 learn more about the subject of
"? NET, lem, guantity; behaviors: veri: — ce ptually. The object definitions are o.- Brammer the code can add or delete in- these artici et O

[y, process, back-order, add. Age ventory items. nase ih please call The James
| Forcer, add. ganized in a class hierarchy, as shown in Pain Martin Report, an information ser
An important, distin needs ne figure ze | Y, | Each of the inven types | | tnformation service
made between a class obe HI Ba sne Pure A casa above sn objeri la ite... lo respond to tle ana va vpooled darterly, at (800) 242.1240.

Bb ; Ve to respond to the mescaga "ah ;

sraiih usod uperclass, and the one below is a sub. Roj message, check For information on sem; ' ple:
Particular objects, The definition: ata Men Su reorder," Each of the particular tu aaa on semtnars, please
class of object "order" cp sec of ine class. Objects in subclasses can inherit would define veheck particular ty contact (in the United States and Can-

tion of the property variables. Each par- pije sl Ta properties and applies to that object, or bodem 4 Dee ada) Technology Transfer institute, —
Ucular object, contains just the values The rs ol lhe classes above, ral check-reorder behaviors f mo 741 10th ne Santa Monica, Calif.
[or he variables of that object. Mes- ject ? programmer working with an ob.  superelasse sa HOT8 rom 90402 (213) 394.8305. m, Europe, con-

, si riented language defines classes seli ses, Th plexity of differing  tact Sava 2 Ne 1
SABeS are sent to t | a aB es c of reorder policies js c. sly | ni, Z New St., Carn,
n he particular object, objects ranging from the general down from zisč aa, of tna ni lasoenu n, dei oi PA United Klepet.
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