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Problem solving process whose objectiveis to :
find and describe a way to implement thesystems functional
requirements
while respecting the constraints imposed bythe quality, platform
and process
requirements (including the budget anddeadlines), and
while adhering to general principles of goodquality.
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Part of design space, showing alternative
designs resulting from different choiceswhen making
decisions.
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We design module !
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In top-down design, you start with the very high-level structure
ofthe system.
Examples of high-level issues that are approached first in
top-down design include the software architecture and the kind
ofdatabase that will be used.
After many higher-level decisions are made, you finally arrive
atdetailed decisions such as the format of particular data
items,and the individual algorithms that will be used.
bottom-up design, involves first making decisions about
reusablelow-level utilities and then deciding how these will be
puttogether to create high-level constructs.
Conclusion: Mix it up !!!
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8/3/2019 #12. OO Principle 1
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Dont conquer everything, instead of it, divide into
smallerproblems and then we may conquer it (paralelly)
Example:
Cars are also built using the divide and conquer strategy:some
people design the engines while others design thebody
Pada projek paperless office dengan fitur yang dimintaoleh user
berupa SPPD & Disposisi Online serta ManajemenRapat,
diidentifikasi tiga hal yang harus dibuat segerayaitu Flow
dokumen/proses bisnis, struktur data/dokumendan prototyping.
Sehingga dibutuhkan tiga tim kecil untukmenyelesaikan ketiga hal
tersebut secara paralel/semiparalel.
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7 2 9 4 2 4 7 97 2 2 7 9 4 4 9
7 7 2 2 9 9 4 4
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divide and conquer to divide things
up into smaller chunks.
Cohesion says to do it intelligently yes,
divide things up, but keep things
together that belong together.
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8/3/2019 #12. OO Principle 1
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Utility : Related utilities are kept together, when there is no
way to group them using a stronger form of
cohesion
Temporal : Procedures used in the same general phase of
execution, such as initialization or termination, arekept together.
Everything else is kept out
Procedural : A set of procedures, which are called one after
another, is kept together. Everything else is keptout
Sequential : A set of procedures, which work in sequence to
perform some computation, is kept together.Output from one is input
to the next. Everything else is kept out
Communicational : Facilities for operating on the same data are
kept together, and everything else is keptout. Good classes exhibit
communicational cohesion
Layer : Related services are kept together, everything else is
kept out, and there is a strict hierarchy in whichhigher-level
services can access only lower-level services. Accessing a service
may result in side effects
Functional : Facilities are kept together that perform only one
computation with no side effects. Everythingelse is kept out
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Silakan dicari sendiri ...
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No dependencies Loosely coupled-some dependencies
Highly coupled-many dependencies
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High Coupling
Loose
Low
Content
Common
Control
Stamp
Data
Routine Call
Type use
Inclusion / import
External
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Silakan dicari sendiri
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8/3/2019 #12. OO Principle 1
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Abstractions are needed because thehuman brain can process only
a limitedamount of information at any one time
Abstraksi level tinggi: class dari domainpermasalahan (sudah
pernah dibahas
).
Contoh abstraksi yang lebih rendah :method abstraction, data
abstraction
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8/3/2019 #12. OO Principle 1
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Design forreuse, and the second is todesign with reuse
(complementary)
Important strategies for increasingreusalbility:
Generalize your design as much as possible.Contoh : method for
drawing 2D shapes.
Follow the preceding three design principles.
Design your system to contain hooks.
Simplify your design as much as possible.
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8/3/2019 #12. OO Principle 1
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Basic Unix commands such as grep, cat,head, tail, sort, uniq,
awk, and sed
Their simplicity comes from the fact thatthey all input and
output the same datatype: streams of characters.
Their power comes from the fact that theycan be strung together
in a large variety ofcombinations.
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Thank you
