Using Caché Objects - InterSystems Documentation

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Methods Write dog.Speak() Which could result in the following code being generated: Write "Woof, Woof" It is a good idea to give all formal variables of an expression method default values. This prevents potential inline substitution problems caused by missing actual variables at runtime. Note: Caché does not allow macros or call-by-reference arguments within expression methods. 6.7.3 Call Methods A call method is a special mechanism to create method wrappers around existing Caché routines. This is typically useful when migrating legacy code to object-based applications. Defining a method as a call method indicates that a specified routine is called whenever the method is invoked. The syntax for a call method is: Method Call() [ CodeMode = call ] { Tag^Routine } where “Tag^Routine” specifies a tag name within a routine. 6.7.4 Method Generators A method generator is actually a small program that is invoked by the Class Compiler during class compilation. Its output is the actual runtime implementation of the method. Method generators provide a means of inheriting methods that can produce high performance, specialized code that is customized to the needs of the inheriting class or property. Within the Caché library method generators are used extensively by the data type and storage classes. For details refer to the Method Generators chapter. 44 Using Caché Objects
7 Properties Properties are the class members that define the state of an object. The manner in which you can access and manipulate the values of an object's properties depends on the object's class definition. Formally, there are two kinds of properties: • Attributes, which hold values • Relationships, which hold associations between objects Within Caché, attribute properties are simply referred to as “properties” while relationship properties are referred to as “relationships.” Many object languages such as Java and C++ do not have true properties, but rather private variables manipulated by public accessor methods. In Caché, properties are different than variables. There is a rich model for properties in which: • Properties can be literal values, collections of literal values, streams, references to persistent objects or embedded objects, or collections of references to persistent objects or embedded objects. • Properties automatically have a set of property methods supporting validation and storage. • Properties can transparently invoke sophisticated translations and other advanced functionality during data retrieval and storage. • Properties automatically pull embedded and persistent objects into memory as soon as they are referenced. This is called “swizzling” (sometimes referred to as “lazy loading” ). Every property has a name, a type, an optional set of modifying keywords, and an optional set of parameters for its type. A property name must be unique within its class. Using Caché Objects 45
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Using Caché Objects Version 5.2 01
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Table of Contents 1 Introduction to
Page 5 and 6: 7 Properties ......................
Page 7 and 8: 13.1 Inheritance and SQL ..........
Page 9 and 10: 20.8 %OnNew .......................
Page 11 and 12: List of Figures Embeddable Objects
Page 13 and 14: 1 Introduction to Caché Objects Th
Page 15 and 16: 1.2 Class Definitions and the Class
Page 17 and 18: Development Tools Caché Class Libr
Page 19 and 20: • The Caché EJB Binding—a vers
Page 21 and 22: 2 Object-Oriented Database Developm
Page 23 and 24: Encapsulation Caché exploits inher
Page 25 and 26: 3 The Caché Object Model The Cach
Page 27 and 28: Referring to an Object — OREF, OI
Page 29 and 30: Types of Classes 3.2.1 Transient Ob
Page 31 and 32: Types of Classes Embeddable Objects
Page 33 and 34: A class inherits all of the specifi
Page 35: 2. It resolves inheritance—it det
Page 38 and 39: Caché Classes • Class Parameters
Page 40 and 41: Caché Classes ClientDataType Descr
Page 42 and 43: Caché Classes Internally, this wor
Page 44 and 45: Packages Class Packages Any of thes
Page 46 and 47: Packages Letting the compiler resol
Page 48 and 49: Packages • “%Library” —any
Page 50 and 51: Methods where count and state are d
Page 52 and 53: Methods 6.4 Method Language You hav
Page 54 and 55: Methods 6.6 Instance and Class Meth
Page 58 and 59: Properties 7.1 Property Keywords Yo
Page 60 and 61: Properties Property Behavior The pr
Page 62 and 63: Properties 7.5 Attribute Properties
Page 64 and 65: Properties You can manipulate a col
Page 67 and 68: 8 Class Queries Class queries provi
Page 69 and 70: Query Basics Final Specifies that s
Page 71 and 72: Caché ObjectScript. These queries
Page 73 and 74: The data in Row is the result of ex
Page 75 and 76: 9 Indices Indexes provide a mechani
Page 77 and 78: Index Collation 9.2 Index Collation
Page 79 and 80: 10 Using Objects with Caché Object
Page 81 and 82: Executing Methods 10.1.3 Executing
Page 83 and 84: Opening Objects 10.3 Opening Object
Page 85 and 86: where oref is the OREF of the speci
Page 87 and 88: For example, to populate the Home p
Page 89 and 90: change the second vaccination recor
Page 91 and 92: There are two types of array proper
Page 93 and 94: Saving Objects 10.5 Saving Objects
Page 95 and 96: mation. Again, this method deletes
Page 97 and 98: Set rset = ##class(%ResultSet).%New
Page 99: Executing Queries // Create a Resul
Page 102 and 103: Data Types 11.1 Available Types Cac
Page 104 and 105: Data Types • INDEXSUBSCRIPTS —
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Data Types CLIENTDATATYPE Values Va
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Data Types SQLCATEGORY Values Value
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Data Types The property is restrict
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Object Persistence 1. Its primary (
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Object Persistence Note: In a multi
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Object Persistence // Open person "
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Object Persistence For example: //
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Object Persistence If a persistent
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Object Persistence The storage clas
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13 Objects and SQL A key aspect of
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The Object-SQL Projection 13.2 The
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The Object-SQL Projection 13.2.2.1
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The Object-SQL Projection • The p
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If the list for a particular instan
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Triggers are, however, fired by the
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14 Relationships A relationship is
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Relationship Basics the relationshi
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An Invoice class class MyApp.Invoic
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14.4 Persistent Behavior of Relatio
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Streams Stream data may be stored i
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Streams 15.2.2 Copying Data between
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Streams Set stream=##class(%Stream.
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16 Class Projections Class projecti
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RemoveProjection The RemoveProjecti
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17 Object Synchronization Object sy
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About Updates • If two changes re
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About Updates Two Synchronized Data
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• classname is a quoted string th
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Set Status = TargetSyncSet.Import(f
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18 Method Generators A powerful fea
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Method Generator Context 6. It copi
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Implementing Method Generators 3. A
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The Caché Data Population Utility
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Using Callback Methods Since differ
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Using Callback Methods ReturnValue
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Using Callback Methods 20.6 %OnDele
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Using Callback Methods 20.10 %OnRol
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21 Object-Specific ObjectScript Fea
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##this Syntax >Do ##class(Package.C
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##super Syntax 21.4 ##super Syntax
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You can override a property's defau
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Dynamic Dispatch 22.2 Content of Me
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Dynamic Dispatch %DispatchMethod ca
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23 Class Definition Classes The Cac
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You can get detailed information ab
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Internet Classes addressed to , its
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Internet Classes For more informati
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Object Concurrency Setting 1 2 3 4
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Object Concurrency Note: You can us
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