UML syntax: Feature

[ronaldtse]

Features

• Def.- A feature describes a structural or behavioral characteristic of a classifier’s instances.
• A structural feature is an abstract metaclass, which describes a typed structure of an instance of a classifier.
  • To prevent a structural feature from being changed, you can specify that it be {readonly}.
  • In the opposite, a changeable structural feature can be specified with {unrestricted}.

Features

• A behavioral feature is an abstract metaclass, which means that an instance of a classifier can respond to requests by calling certain behavior.
• More specifically, parameters can be passed to requests and returned.
• A behavior can also thrown an exception.
• An operation is a common example of a behavioral feature.

Features

• A parameter is the specification of an argument that is passed by a behavioral feature or returned by this behavioral feature.
• A parameter has a type, a multiplicity and a direction.
• Optionally you can state a default value and a name.

Features

• The direction of a parameter is specified by use of the keywords in, out, inout or return.
• The default value in is assumed if no direction is stated.

--|-- |In  | The caller passes the parameter value to the behavior |Out | The behavior passes the parameter value to the caller |Inout | The caller first passes the parameter value to the behavior, which returns it to the caller |Return | Similar tu out, except that return explicitly specifies the return values of the behavior

Features-notation

• The syntax of a parameter looks like this: [direction] name:type [multiplicity] [=default] [{property string}]
• The property string for a parameter can be one of the values known for properties, such as {ordered} and {nonunique}.

From https://www.linkedin.com/learning/software-design-modeling-with-uml/class-diagrams-classifiers-and-features?autoplay=true&resume=false

Proposal:

class BankAccount {
  +accountNumber: string[1] {id, readonly}
  -ssn: string[1..5] {unique}

  +deposit(in amount:float): float
  #calcMonthlyAverageBalances(inout monthlyBalances float[12]): void
}

[w00lf]

class BankAccount {
  +accountNumber: string[1] {id, readonly}
  -ssn: string[1..5] {unique}

  +deposit(in amount:float): float
  #calcMonthlyAverageBalances(inout monthlyBalances float[12]): void
}

@ronaldtse Just spotted a problem here. We use # as a comment notation, so we cant use it a visibility modifier, what should we do in that case? Change comment notation or introduce other way to define protected method? We can change comments to use explicit comment keyword:

class Pet {
   comment 'number of legs of a pet'
   attribute number
}

11

[ronaldtse]

I did not realize that # can be a visibility modifier. Can we use something like % or > (latex uses % for comments, idris uses >)?

[w00lf]

I did not realize that # can be a visibility modifier. Can we use something like % or > (latex uses % for comments, idris uses >)?

Lets use % in that case

[ronaldtse]

Awesome, then this is set. @w00lf could you help update the documentation? Thanks!

[w00lf]

Awesome, then this is set. @w00lf could you help update the documentation? Thanks!

Sure, i am updating it as we go