Chapter 5. A Model Expressed In Software Flashcards by Val M

An association in the model means there is what in the software?

A mechanism with the same properties.

DDD, p. 82

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Three ways to make associations more tractable are:
Impose a ________ direction
Add a _________ (effectively reducing multiplicity)
Eliminate _________ associations

traversal direction. (e.g a country has a president)
Add a qualifier, (e.g,, a country has only one president during a particular period)
nonessential associations

DDD, p. 83

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An object defined primarily by its identity is called an __________.

Entity

DDD, p. 91

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For an entity, an identifying attribute must be guaranteed to be _______ within the system.

Unique

DDD, p. 92

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For an entity, an identifying attribute must be guaranteed to be _______ within the system.

Unique

DDD, p. 92

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Value objects are instantiated to represent elements that we care about only for ________ they are, not _________ or _______ they are.

What
Not who or which

DDD, p. 98

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When creating property for value object in Obj-C , the defaulting qualifier is which: atomic or nonatomic?

Nonatomic

ObjC.io issue on Foundation, Value Objects

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By default properties are Strong or Copy?

Strong

ObjC.io issue on Foundation, Value Objects

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Where else could the ‘copy’ qualifier be assigned?

in the implementation.
_name = [ name copy ];

ObjC.io issue on Foundation, Value Objects

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For an immutable object, when do you want to assign Copy to a property?

When there is a mutable counterpart to the type. E.g. string
@property (nonatomic,copy) NSString* name;

ObjC.io issue on Foundation, Value Objects

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How can you compare to value objects?

implement the isEqual method using all properties and implement a hash function

ObjC.io issue on Foundation, Value Objects

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What is a hash?

a pseudorandom number generated from the object’s properties.

ObjC.io issue on Foundation, Value Objects

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What are two good qualities of a hash?

deterministic and uniform

ObjC.io issue on Foundation, Value Objects

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If the properties that go into a hash value change, what else changes?

the hash value… bad… make sure things are immutable

From objc article on value objects

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The code should contain an _________ that is guaranteed to produce a ________ result for each entity object.

operation
unique

DDD, p.92

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How are properties a convenience for objective-c programmers?

when synthesizes, properties give you automatic getters and setters.

inferred from iOS programming (Big Nerd), p. 72

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How many property attributes are there?

Three

iOS programming (Big Nerd), p. 72

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Most objective-c programmers use which of these: atomic or nonatomic?

Nonatomic

iOS programming (Big Nerd), p. 73

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When would you use atomic as a property value?

for multi-threaded applications.

iOS programming (Big Nerd), p. 73

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Which is the default property? Atomic or nonatomic.

Atomic. Will always need to explicitly declare nonatomic.

iOS programming (Big Nerd), p. 73

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Multi-threaded or concurrent programming allows you to take advantage of multiple _______.

CPUs

ObjC.io issue on Concurrent Programming, Editorial

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Which is the default property qualifier: readwrite or readonly?

readwrite

iOS programming (Big Nerd), p. 73

Which property qualifier would you want to use for a value object? : readwrite or readonly

Readonly. This makes them immutable which is a required characteristic of value objects.

ObjC.io issue on Foundation, Value Objects

Which of these property qualifiers is default: strong or assign?

It depends on the type of property!

iOS programming (Big Nerd), p. 73

A property whose type is not a pointer to an object (scalar property), like -int-, does not need memory management and thus defaults to which one: strong or assign?

assign iOS programming (Big Nerd), p. 73

For pointers to objects which is the default: strong or assign?

strong iOS programming (Big Nerd), p. 73

When you have a property that points to an instance of a class that has a mutable subclass (like NSString or NSArray) which should be the qualifier: strong or copy?

Copy iOS programming (Big Nerd), p. 76

When pointing at a mutable subclass and not using copy, the item can be ________ without knowledge of the object that also points to it.

changed. iOS programming (Big Nerd), p. 77

Bidirectional associations do or do not make sense between value objects?

do not make sense because you could not say that one value objects points directly to the one pointing to it - no identity. DDD, p. 102

When we force an operation into an object that doesn't fit the objects's definition, the object loses its ___________ and becomes hard to understand or ___________.

conceptual clarity refactor DDD, p. 104

One should use a service when _________ is actually an important domain concept.

an operation DDD, p. 105.

In object oriented programming, an interface generally defines the set of ________ that an instance of a class that has that_______ could _______ to.

the set of methods (or messages) interface respond. http://stackoverflow.com/questions/2866987/what-is-the-definition-of-interface-in-object-oriented-programming

When you write an interface, you're basically saying:

"I need something that..." http://stackoverflow.com/questions/2866987/what-is-the-definition-of-interface-in-object-oriented-programming

A good service relates to a __________ that is not a natural part of an _______ or _________.

domain concept entity value object DDD, p. 105

A good service is an _________ that is defined in terms of the __________ in the domain model.

interface other elements DDD, p, 105

T/F A good service is stateless.

True DDD, p, 105

For a service, statelessness means that any ________ can use any instance of a particular service without regard to the instance's ______________.

client individual history (If a class Cheetos Bag implements the Chip Bag interface, you should expect a Cheetos Bag to behave exactly like any other Chip Bag. (That is, expose the .attemptToOpenWithoutSpillingEverywhere() method, etc.) DDD, p. 105

An interface indicates ________ of the object that implements the interface.

capability (Walkable might be a good interface to have if your system has many things that can walk.) http://stackoverflow.com/questions/444245/how-will-i-know-when-to-create-an-interface

T/F A service should be implemented as a phony object.

False, this would be misleading. DDD, p. 105

Services can appear in which layers?

Application, domain, or infrastructure DDD, p. 106

If the operation for a service has any meaning in the domain then it should be in the ______.

Domain model DDD, p.106

What is meant by "clients" in the OOP world?

In the gof book, the client is the code or class that is using the classes in the pattern. http://stackoverflow.com/questions/15847806/client-concept-in-oop-design-patterns

A distributed system is a ________ of independent computers that appears to its users as a _________ system (Tanenbaum, van Steen)

collection single, coherent http://www.win.tue.nl/~johanl/educ/2II45/ADS.02.Distributed.pdf

The primary motivation for using modules is ___________.

cognitive overload DDD, p.109

There should be _______ cohesion between modules and _____ cohesion within them.

low high DDD, p,109

True / False: Modules (packages) can be implemented in Objective-C.

False. http://stackoverflow.com/questions/1000707/objective-c-equivalent-of-java-packages

Refactoring modules are more or less work than refactoring classes?

More DDD, p.110

If your model is telling a story, the modules are _______.

chapters DDD, p.110

With packages, Java can have two _______ with the same name "connection"

Classes e. g., com. cod3r.app.network.Connection and com.cod3r.app.database.Connection

In Java, the_____ name gets longer where as in Objective-C the ______ name gets longer.

package class http://www.cod3r.com/2011/01/what-objective-c-can-learn-from-java-part-4-namespace/ for a helpful overview of packages in Java see: http://docs.oracle.com/javase/tutorial/java/package/index.html

The difference is [in Java] the fully qualified ________ would only be used in the _____ statement, and the short _______ would be used in the code, instead of the _______ used in every location as seen in Objective-C.

``` class name short class name really long classname ``` http://www.cod3r.com/2011/01/what-objective-c-can-learn-from-java-part-4-namespace/

Most systems must use some non object technical infrastructure, most commonly ___________.

relational databases DDD, p. 120

The most effective tool for holding the parts [from mixed paradigms] together is a robust _________ that underlies the whole heterogeneous model.

ubiquitous language DDD, p. 121

Before taking on the burden of mixed paradigms, the options within the _________ should be exhausted.

dominant paradigm DDD, p. 122