2. The Utilities Library

Namespace: model://perspectives.domains#Utilities.

2.1. GenSym

GenSym()

Generate a random symbol.

callExternal util:GenSym() returns String
Parameter/Result Type Explanation

result (functional)

String

A random string.

2.2. RoleIdentifier

<roleExpression> >> RoleIdentifier()

RoleIdentifier(role)

Returns the internal identifier of a role instance.

callExternal util:RoleIdentifier( Visitor ) returns String
Parameter/Result Type Explanation

role

RoleInstance

An instance of a role.

result (functional)

RoleIdentifier

An identifier like "def:#defe6263_7ebf_43d1_ae9d_25d3f8146d05".

2.3. ContextIdentifier

<contextExpression> >> ContextIdentifier()

ContextIdentifier( <context> )

Returns the internal identifier of a context instance.

callExternal util:ContextIdentifier( Chat ) returns String
Parameter/Result Type Explanation

context

ContextInstance

An instance of a context.

result (functional)

ContextIdentifier

An identifier like "def:#defe6263_7ebf_43d1_ae9d_25d3f8146d05".

2.4. SystemIdentifier

systemIdentifier()

Returns the string that identifies a particular installation. It is not a Resource Identifier (it doesn’t have a storage scheme prepended, e.g. "def:#blablabla" - it is just "blablabla")

Parameter/Result Type Explanation

result (functional)

String

The raw identifier of the installation. The ID of the PerspectivesSystem instance is constructed from it.

 
callExternal util:SystemIdentifier() returns String

2.5. Replace

<valueExpression> >> Replace( <target>, <replacement> ) returns String

Replace( <target>, <replacement>, <value> ) returns String

Replace parts of a string with another string.

Parameter/Result Type Explanation

target

String

A literal string to find and replace in the value.

replacement

String

A string to replace the matches with.

value

String

The string value in which the replacement takes place.

result (functional)

String

The string with the replacement.

 
callExternal util:Replace( ".", "_", Repositories$NameSpace ) returns String

2.6. ReplaceR

<valueExpression> >> ReplaceR( <pattern>, <replacement> ) returns String

ReplaceR( <pattern>, <replacement>, <value> ) returns String

Replace parts of a string with another string.

Parameter/Result Type Explanation

pattern

Regular expression

A regular expression in string form, like the parameter of the Javascript RegExp object.

replacement

String

A string to replace the matches with.

value

String

The string value in which the replacement takes place.

result (functional)

String

The string with the replacement.

 
callExternal util:ReplaceR( "\\$.*$", "NewName", Repositories$NameSpace ) returns String
Note
 to use a character class like \n in a regular expression, escape the backslash (\) character with another backslash, like this: \\n.

2.7. SelectR

<valueExpression> >> SelectR( <pattern> ) returns String

SelectR( <pattern>, <value> ) returns String

Select part of a string.

Parameter/Result Type Explanation

pattern

Regular expression

A regular expression in string form, like the parameter of the Javascript RegExp object.

value

String

The string value to select from.

result (functional)

String

The selected substring.

 
callExternal util:SelectR( "#(.*)", Repositories$NameSpace ) returns String
Note
 to use a character class like \n in a regular expression, escape the backslash (\) character with another backslash, like this: \\n.

2.8. Random

<numberExpression> >> Random( <lowerBound> ) returns Number

Random( <lowerBound>, <upperBound> ) returns Number

Returns a random integer between lower- and upperbound.

Parameter/Result Type Explanation

lowerBound

Integer

upperBound

Integer

result (functional)

String

Result will be a random integer uniformly distributed in the closed interval [low, high].

 
callExternal util:Random( "1", "10" ) returns Number

2.9. FormatDateTime

<stringExpression> >> FormatDateTime( <date>, <locale> ) returns String

FormatDateTime( <date>, <locale>, <options> ) returns Number

Format a date.

Parameter/Result Type Explanation

date

DateTime

A DateTime Value(see below).

locale

String

A locale according to the [specification], e.g. "en-EN" or "nl-NL".

options

String

This should be the serialisation of a JSON object: all identifiers and string are required to be in double quotes and these quotes must be escaped by a backslash to prevent breaking the surrounding string.

result (functional)

String

A string that shows the date (and optionally time) in the required format.

DateTime (PDate) values can be entered literally in Perspectives Language, or can be entered through the user interface, or can be read from the system clock (see the Sensor library, device "clock", sensor "now"). For the form of the literal representation see DateTime String Format on MDN. Summary: the type must conform to YYYY-MM-DDTHH:mm:ss.sssZ, but time may be left out.

The options object may contain any key-value pairs as specified in this ECMA specification.

For a discussion of the locale and the options object, see DateTimeFormat on MDN.

callExternal util:FormatDateTime( SomeDate, "nl-NL", "{\"dateStyle\": \"full\", \"timeStyle\": \"short\"}" ) returns Number

2.10. EvalExpression

<roleExpression> >> EvalExpression( <expression> ) returns String

EvalExpression( <expression>, <role> ) returns String

Parse, compile and evaluate an expression with respect to a particular role instance.

Parameter/Result Type Explanation

expression

String

A Perspectives Language query expression such as can be used in models for calculated properties.

role

roleInstance

A role instance.

result (unknown)

String

A string representation of the result of the query, whatever its Range type is.

 
callExternal util:EvalExpression( "1 + 3" ) returns Number
callExternal util:EvalExpression( TotalNumberOfItems / 5 ) returns Number

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