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Class - Defining a Class

2025-04-04T00:11:22Z

Eleanor.McFeaters: /* Syntax for Instance Definition */

[[Category:PGM]]
{{Navigation|[[PGMs]]|altname=Classes}}
{{Function Header Tabs |currentpage=8}}

'''Related Links:''' [[Example_PGM_Files#User_Defined_Class_and_Functions|User Defined Class and Functions]], [[Example_PGM_Files#User_Defined_Class_and_Functions|Example PGM Files]]
{{Class Header Tabs|currentpage=2}}
'''Global Predefined Class Instances:''' [[Species Database Class]], [[Particle Size Definition Class]], [[Plant Model Class]] 
'''Predefined Classes:''' [[Array Class]], [[StrArray Class]], [[Matrix Class]], [[TagSelect Class]], [[Noise Class]], [[TimeClass]]
----
{{TOC}}

== Syntax for Class Definition ==
{|
|Valign=top width=20%|
<syntaxhighlight lang="pgm">Class className

;Variable declaration(s)

;Sub(s) and Function(s)

EndClass</syntaxhighlight>
|width=80%|
===Syntax for Class Declaration===
*<syntaxhighlight lang="pgm" inline>Class</syntaxhighlight>: The class declaration must begin with the '''Class''' keyword
*<syntaxhighlight lang="pgm" inline>EndClass</syntaxhighlight>: The class declaration must end with the '''EndClass''' keyword.
*'''className''': A globally unique class type name must be provided. This is later used as a "data type" when declaring instances of classes of this class type. See [[#How to use the Class (Class Instances)|How to use the Class]].
*TextLabel can be used within the class for arranging display of variables in the Access window.
*ClassAsPageLabel keyword can be used to automatically create tab pages in the Access window based on class instance name.

*Note that Class definitions cannot be nested (i.e. classes cannot be defined within the definition of a class).
*Various PGM language commands are unavailable within a class definition.

|}

===Syntax for Class Variable Declaration===
*Variables can be declared within the class, their scope is limited to the class, and they are available to the instance of the class.
*When declaring variables in a class, the normal variable declaration rules will apply:
*: The user can define units.
*: Append * or @ to make the variable visible in the access window, and writeable (*) or read-only (@).
*: For more information, refer to [[Declaring Variables|Variable declaration]].
*Variables of type class can be declared within the class. These may be SysCAD PGM classes (e.g. Matrix Class) or user defined classes.

===Syntax for Subs and Functions in a Class===

Any number of functions (of type Sub, Function and StrFunction) can be declared within the class and they are available to the instance of the class. The sequence of functions and variables within a class can be mixed and arranged as required.

Typically, a class will have these three types of subroutine in it:
*Initialise subroutine
*Calculation subroutine(s)
*Execute subroutine

===Special Functions===
These Special Functions are available for use within class functions and subroutines:
*<syntaxhighlight lang="pgm" inline>ClassName()</syntaxhighlight> : returns a string of the class type name. In example below, this will return "CSTR_Class".
*<syntaxhighlight lang="pgm" inline>ClassTag()</syntaxhighlight> : returns a string of the class instance variable name (tag). This is a particularly useful function when the class instance variable name matches a tag in the model.
*:For example, we can use "UnitTag = ClassTag()" within an "Init()" Sub for the class. See [[#Example Class Definition File|Example Class Definition File]]

=== Formatting Keywords ===
{{Available139|32530}} The following optional formatting keywords can be added in the Class definition. They are used to help manage how the class instance and its variables are displayed in the Access window. See [[#Class_Instance_Variable_Display_Options|Class Instance Variable Display Options]] for more information.

General keywords:
*<syntaxhighlight lang="pgm" inline>ClassAsGroup</syntaxhighlight>: If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed as a group in the Access window.
*<syntaxhighlight lang="pgm" inline>ClassAsPageLabel</syntaxhighlight>: {{Available139|31388}} If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed on a new tab page in the Access window, with the page name matching the class instance name. The user does not need to specify PageLabel(xxx) for each class. It is also useful for each class instance in an array of classes appearing on a new tab page.
*<syntaxhighlight lang="pgm" inline>ClassAsTextLabel</syntaxhighlight>: If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed with a text label (heading) in the Access window, with the text label matching the class instance name.

Grid display keywords:
*<syntaxhighlight lang="pgm" inline>ClassGridColumnWidth Width</syntaxhighlight>: Use this to change the default width of each column displayed in a class grid.
*<syntaxhighlight lang="pgm" inline>ClassGridMaxColumns MaxColumns</syntaxhighlight>: Use this to change the maximum number of columns allowed before a new grid is automatically created.
*<syntaxhighlight lang="pgm" inline>ClassGridHideComment</syntaxhighlight>: Use this to hide the display of class instance comments, that are normally displayed in the first row of the grid.
*<syntaxhighlight lang="pgm" inline>ClassGridHideText</syntaxhighlight>: Use this to hide the display of all TextLabels shown as text between rows in the grid.

Instead of using the above formatting keywords within the class definition, they can be included within {} when defining the class name. The full keyword or shortened formats can be used. These are ClassAsPageLabel|AsPageLabel|pl, ClassAsTextLabel|AsTextLabel|tl, ClassAsGroup|AsGroup|g, ClassGridColumnWidth|ColumnWidth|Width|cw, ClassGridMaxColumns|MaxColumns|mc, ClassGridHideComment|HideComment|hc ClassGridHideText|HideText|ht. 
Example: <syntaxhighlight lang="pgm" inline>class TankClass{g,pl,cw(12),mc(6)}</syntaxhighlight>

==Syntax for Class Instance Definition==
Once the Class has been defined (template complete), the user can include this named class definition (template) in pgm files to declare any number of class instances. Class instances are then used in subsequent to code to perform calculation acting on the individual class instances. Class instances can be declared '''individually''' (in the same way normal data variables are declared) or as an '''array''' of class instances:
* Example of individually named class instances: <syntaxhighlight lang="pgm" inline>CSTR_Class Tank_1, Tank_2</syntaxhighlight> See [[#Declaring_Class_Instances|Example - declaring class instances]].
* Example of class array: <syntaxhighlight lang="pgm" inline>CSTR_Class Tank[3]</syntaxhighlight> See [[#Declaring Class Instances in an array|Example - Declaring Class Instances in an array]].

===Syntax for Interacting with Class Instances===
Once the class instance has been declared, user can access class variable tags and perform the Class functions or subroutine.

* Setting a value to a data member of an instance.
*:For example, we can set the UnitTag for class instance "TankA" during the "InitialiseSolution()" subroutine: <syntaxhighlight lang="pgm" inline>TankA.UnitTag = "TANK_A"</syntaxhighlight>.
* Retrieving the value of a data member of an instance.
*:For example: we can retrieve a value from a class function and assign it to a variable: <syntaxhighlight lang="pgm" inline>ReactionExtent = TankA.CuLeachExtent</syntaxhighlight>
* Retrieving the value returned by a member function of an instance.
*:For example: we can get the species index of water from the [[Species Database Class]]: <syntaxhighlight lang="pgm" inline>SpeciesIndex = SDB.FindSpecies("H2O(l)")</syntaxhighlight>
* Performing Class Function / subroutine calculations.
*:For example, we can perform the Exec() function for class instances Tank_A and Tank_B:
*:<syntaxhighlight lang="pgm" inline>Tank_A.Exec()</syntaxhighlight>
*:<syntaxhighlight lang="pgm" inline>Tank_B.Exec()</syntaxhighlight>

If user have declared many class instances, it will be quite tedious to define each function call separately. To execute some of these functions more efficiently, we have added some special "ForEach" [[#Class Macros|macros]]. For example:
*'''ForEachSub''' (previously ForEachClass) Macro Function: used to call subroutines for all instances of the class.
*'''ExcludeClass''' Used to block class from use in ForEach macro. Commonly used to block instance at index 0 in an array of classes.
*'''ClassList''' Used to define a list of class instances as aa single variable and then use this with ForEach Macros and ForEach Macro Functions.

== Class Instance Variable Display Options ==

When class instances are declared, any watched variables will be available on the access window.
*When declaring the class instances, '''*''' or '''@''' CANNOT be appended to the class instance name.
*Class instances are automatically added to the access window.

=== ExcludeWatch ===
To hide a specific class instance from the access window display, use '''ExcludeWatch''' followed by one or more ClassNames. A comma separated list of any number of class instances, including indexed class instances of a class array can be listed. 
Syntax is: <syntaxhighlight lang="pgm" inline>ExcludeWatch ClassInstance1,...</syntaxhighlight> 
For example: <syntaxhighlight lang="pgm" inline>ExcludeWatch Tank[0]</syntaxhighlight>

ExcludeWatch is primarily used for hiding the the class at index 0 within a class array as shown in above example. From Build 139.32530 it is possible to define this when declaring the class array using {ExcludeWatchZero} or {ewz}. However because it is very common to use both ExcludeClass and ExcludeWatch, then use {ExcludeZero} or {ez}. For example: 
<syntaxhighlight lang="pgm">const long TankCount = 11
TankClass T[TankCount]
ExcludeWatch T[0]
ExcludeClass T[0]
;From Build 139.32530 the above can be replaced by
TankClass T[TankCount]{ewz,ecz} ;or in full {ExcludeWatchZero,ExcludeClassZero}
;or simply the common combined form:
TankClass T[TankCount]{ExcludeZero} ;using full keyword
TankClass T[TankCount]{ez} ;using abbreviated keyword</syntaxhighlight>

=== ClassComment ===
After class instances have been declared, '''ClassComment''' can be used to specify short text comments for Class Instances (similar to text comment for individual variables). A comma separated list of any number of class instances (including indexed class array instances) with text string in quotes (") can be listed. The display of the comment in the Access window depends on use of ClassAsGroup and if class is shown in Grid. 
Syntax is: <syntaxhighlight lang="pgm" inline>ClassComment ClassInstance1 "String1",...</syntaxhighlight> 
For example: <syntaxhighlight lang="pgm" inline>ClassComment T[1] "Feed tank"</syntaxhighlight>

ClassComment is primarily used for specifying comments for class instances within a class array as shown in above example. In most cases it is more common to include the comment with the declaration of the individual class instance. 
For example:<syntaxhighlight lang="pgm" inline>TankClass T1{"Feed Tank"}, T2{"Acid Tank"}, T3{"Tank 300-A012"}</syntaxhighlight>

=== General Formatting Keywords ===
{{Available139|32530}} A number of different keywords in the class definition can be used to manage how the class variables for class instances should be displayed in the Access window. General formatting options:
* Use <syntaxhighlight lang="pgm" inline>ClassAsGroup</syntaxhighlight> keyword (recommended) to use the ClassName... group heading for each class instance (and all the variables don't have the repeated ClassName.xxx). This is particularly useful together with a ClassComment for the class instances where the comment is shown in the group heading, displayed as: "ClassName (comment) ...".
* Use <syntaxhighlight lang="pgm" inline>ClassAsPagelabel</syntaxhighlight> keyword to display one Class instance per tab page.
* use <syntaxhighlight lang="pgm" inline>ClassAsTextlabel</syntaxhighlight> keyword to display the class name as a text label heading to "separate" the class instances.

=== ClassGrid ===
{{Available139|32530}} With the keyword '''ClassGrid''', class instances of user defined class types can be displayed in Grids (Tables) in the Access window with the class instances as columns. The ClassGrid keyword is used anywhere after class instances are declared to control where the grids are displayed. It is also possible to use the keyword when [[#Syntax_for_Declaring_Class_Instances|declaring the class instances]].
Syntax is: <syntaxhighlight lang="pgm" inline>ClassGrid Classes</syntaxhighlight> 
Where ''Classes'' is a list of class instances of the same class definition. ''Classes'' can be specified in a number of different methods such as using a previously defined ClassList or list of classes similar to [[#Classes_Parameter|Classes Parameter]] in ForEach macros. 
Example (list of class instances): <syntaxhighlight lang="pgm" inline>ClassGrid {T1,T2,T3}</syntaxhighlight> (where ''T1,T2,T3'' are previously defined instances of the same class definition) 
Example (ClassList): <syntaxhighlight lang="pgm" inline>ClassGrid L1</syntaxhighlight> (where ''L1'' is a previously defined [[#ClassList|ClassList]]) 
Example (class definition type): <syntaxhighlight lang="pgm" inline>ClassGrid {TankClass}</syntaxhighlight> (where ''TankClass'' is a previously defined [[##Syntax_for_Class_Definition|Class Definition]]) 
Example (class array): <syntaxhighlight lang="pgm" inline>ClassGrid Tanks</syntaxhighlight> (where ''Tanks'' is a previously defined [[#Syntax_for_Declaring_Class_Instances|Class Array]])

Notes:
* The width of each column can be controlled with the '''ClassGridColumnWidth''' keyword in the class definition.
* The maximum number of columns in a grid is controlled with the '''ClassGridMaxColumns''' keyword in the class definition. Additional grids are automatically created when there is a larger number of class instances.
* TextLabels within the class grid are shown as row separators, however blank lines and multiple text lines are ignored (only the last TextLabel in a sequence is shown). All text in a grid can be hidden if using keyword '''ClassGridHideText''' in the class definition.
* If comments are used for class instances, these are shown as text for each column in first row of grid. This can be disabled using keyword '''ClassGridHideComment''' in the class definition.
* If option ClassGridPageLabel is used in class definition, then the grid is displayed on a new tab page in the Access window.
* The use of ClassGrid allows positioning of display of the grid in Access window to be at any point after the declaration of class instances. To display the grid at the point of declaring the classes, use the {Grid} option or # symbol.
* Only user defined classes can be used in the ClassGrid. Predefined PGM class types (TagSelect, Matrix, etc.) cannot be used with ClassGrid.
* A class instance can only be displayed once in a grid.

=== ClassGrid Formatting Keywords ===
{{Available139|32530}} A number of different keywords in the class definition can be used to manage how the class grid is displayed in the Access window:
*<syntaxhighlight lang="pgm" inline>ClassGridColumnWidth Width</syntaxhighlight>: Use this to change the default width (14) of each column displayed in a class grid.
*<syntaxhighlight lang="pgm" inline>ClassGridMaxColumns MaxColumns</syntaxhighlight>: Use this to change the maximum number of columns (10) allowed before a new grid is automatically created.
*<syntaxhighlight lang="pgm" inline>ClassGridHideComment</syntaxhighlight>: Use this to hide the display of class instance comments, that are normally displayed in the first row of the grid.
*<syntaxhighlight lang="pgm" inline>ClassGridHideText</syntaxhighlight>: Use this to hide the display of all TextLabels shown as text between rows in the grid.

=== Examples ===
{|
|Valign=top Width=35% rowspan=3|
<syntaxhighlight lang="pgm">
;Class PGM
Class TankClass
;ClassAsPageLabel
;ClassAsTextLabel
;ClassAsGroup
;ClassGridColumnWidth 8 ;default is 14
;ClassGridMaxColumns 3 ;default is 10
;other code here....
String UnitTag{Tag}@
Real Volume*<<100>>("Vol", "m^3")
Real Height*<<1>>("L", "m")
Real ResidenceTime*("Time", "h")
TextLabel()
EndClass

;Main PGM
PageLabel("Tanks")
TextLabel(,)
TankClass Tank1, Tank2
;TankClass Tank[7]
;ClassGrid TankClass
;ExcludeWatch Tank[0]
;ExcludeClass Tank[0]
$</syntaxhighlight>

NOTE: The examples presented to the right uses different options from the above code (currently marked with ;).

|Valign=top|[[image:PGM_ClassDisplay.png|thumb|Using PageLabel keyword only]]
|Valign=top|[[image:PGM_ClassAsPageLabel.png|thumb|Using ClassAsPageLabel]]
|-
|Valign=top|[[image:PGM_ClassAsTextLabel.png|thumb|Using ClassAsTextLabel]]
|Valign=top|[[image:PGM_Classgroup.png|thumb|Using ClassAsGroup]]
|-
|Valign=top|[[image:PGM_ClassGrid.png|thumb|Using ClassGrid]]
|Valign=top|[[image:PGM_ClassGrid2.png|thumb|Using ClassGrid with custom width]]
|}

==Summary Table==
{| class="wikitable"
|
|-
! width = 20%|Function!! width = 20%| Function Syntax !! width = 60%| Description/Notes/Example
|-
| Declaring a Class
| <syntaxhighlight lang="pgm">
Class ClassName
;Class code
EndClass </syntaxhighlight>
|<syntaxhighlight lang="pgm" inline>Class</syntaxhighlight>: The class declaration must begin with the word '''Class'''
<syntaxhighlight lang="pgm" inline>ClassName</syntaxhighlight>: A globally unique class type name must be provided. This is later used as a "data type" when declaring instances of classes of this class type.
<syntaxhighlight lang="pgm" inline>EndClass</syntaxhighlight>: The class declaration must end with the word '''EndClass'''
|-
| Class Variable Declaration
|
| Variables can be declared within the class, their scope is limited to the class, and they are available to the instance of the class.
*When declaring variables in a class, the normal variable declaration rules will apply:
*: The user can define units.
*: Append * or @ to make the variable visible in the access window, and writeable (*) or read-only (@).
*: For more information, refer to [[Declaring Variables|Variable declaration]].
*Variables of type class can be declared within the class. These may be SysCAD PGM classes (e.g. Matrix Class) or user defined classes.

|-
| Syntax for Subs and Functions
| <syntaxhighlight lang="pgm">
Sub SubroutineName()
Function FunctionName()
StrFunction StrFunctionName() </syntaxhighlight>
| Any number of functions (of type Sub, Function and StrFunction) can be declared within the class and they are available to the instance of the class. The sequence of functions and variables within a class can be mixed and arranged as required.
Typically, a class will have these three types of subroutine in it:
* Initialise subroutine
* Calculation subroutine(s)
* Execute subroutine

|-
|rowspan = 3| Special Functions - General Keywords
| <syntaxhighlight lang="pgm"> ClassAsGroup </syntaxhighlight>
|If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed as a group in the Access window.
|-
| <syntaxhighlight lang="pgm"> ClassAsPageLabel </syntaxhighlight>
| Available from Build 139.31388. If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed on a new tab page in the Access window, with the page name matching the class instance name. The user does not need to specify PageLabel(xxx) for each class. It is also useful for each class instance in an array of classes appearing on a new tab page.
|-
| <syntaxhighlight lang="pgm"> ClassAsTextLabel </syntaxhighlight>
| If this keyword is included within the class definition, then later when class instances are declared they are automatically displayed with a text label (heading) in the Access window, with the text label matching the class instance name.
|-
| RowSpan = 5| Specal Functions - Grid Display Keywords
| <syntaxhighlight lang="pgm"> ClassGridColumnWidth Width</syntaxhighlight>
| Use this keyword to change the width of each column displayed in a grid class.
|-
| <syntaxhighlight lang="pgm"> ClassGridMaxColumns MaxColumns</syntaxhighlight>
| Use this keyword to change the maximum number of columns allowed before a new grid is automatically created.
|-
| <syntaxhighlight lang="pgm"> ClassGridHideComment</syntaxhighlight>
| Use this keyword to hide the display of class instance comments that are normally displayed in the first row of the grid.
|-
| <syntaxhighlight lang="pgm"> ClassGridHideText</syntaxhighlight>
| Use ths keyword to hide the display of all TextLabels shown a text between rows in the grid.
|-
| <syntaxhighlight lang="pgm"> ClassAsPageLabel|AsPageLabel|pl, ClassAsTextLabel|AsTextLabel|tl, ClassAsGroup|AsGroup|g, ClassGridColumnWidth|ColumnWidth|Width|cw, ClassGridMaxColumns|MaxColumns|mc, ClassGridHideComment|HideComment|hc ClassGridHideText|HideText|ht</syntaxhighlight>
| Instead of using the above formatting keywords within the class definition, they can be included within {} when defining the class name. The full keyword or shortened formats can be used.
Example: <syntaxhighlight lang="pgm"> class TankClass{g,pl,cw(12),mc(6)}</syntaxhighlight>
|}

==Class Variable Display Options==
When class instances are declared, any watched variables will be available on the access window.
*When declaring the class instances, '''*''' or '''@''' CANNOT be appended to the class instance name.
*Class instances are automatically added to the access window.

{| class="wikitable"
|-
! Width = 20%|Function
! Width = 20%|Function Syntax
! Width = 60%|Description/Notes/Examples
|-
| Exclude Watch
| <syntaxhighlight lang="pgm" inline>ExcludeWatch ClassInstance1,...</syntaxhighlight> 
| To hide a specific class instance from the access window display, use '''ExcludeWatch''' followed by one or more ClassNames. A comma separated list of any number of class instances, including indexed class instances of a class array can be listed. 
For example: <syntaxhighlight lang="pgm" inline>ExcludeWatch Tank[0]</syntaxhighlight> 
ExcludeWatch is primarily used for hiding the the class at index 0 within a class array as shown in above example. From Build 139.32530 it is possible to define this when declaring the class array using {ExcludeWatchZero} or {ewz}. However because it is very common to use both ExcludeClass and ExcludeWatch, then use {ExcludeZero} or {ez}. For example: 
<syntaxhighlight lang="pgm">const long TankCount = 11
TankClass T[TankCount]
ExcludeWatch T[0]
ExcludeClass T[0]
;From Build 139.32530 the above can be replaced by
TankClass T[TankCount]{ewz,ecz} ;or in full {ExcludeWatchZero,ExcludeClassZero}
;or simply the common combined form:
TankClass T[TankCount]{ExcludeZero} ;using full keyword
TankClass T[TankCount]{ez} ;using abbreviated keyword</syntaxhighlight>

|-
| Class Comment
| <syntaxhighlight lang="pgm" inline>ClassComment ClassInstance1 "String1",...</syntaxhighlight> 
| After class instances have been declared, '''ClassComment''' can be used to specify short text comments for Class Instances (similar to text comment for individual variables). A comma separated list of any number of class instances (including indexed class array instances) with text string in quotes (") can be listed. The display of the comment in the Access window depends on use of ClassAsGroup and if class is shown in Grid. 
For example: <syntaxhighlight lang="pgm" inline>ClassComment T[1] "Feed tank"</syntaxhighlight>
ClassComment is primarily used for specifying comments for class instances within a class array as shown in above example. In most cases it is more common to include the comment with the declaration of the individual class instance. 
For example:<syntaxhighlight lang="pgm" inline>TankClass T1{"Feed Tank"}, T2{"Acid Tank"}, T3{"Tank 300-A012"}</syntaxhighlight>
|-
| RowSpan = 3| General Formatting Words
| <syntaxhighlight lang="pgm" inline> ClassAsGroup</syntaxhighlight>
| (Recommended) Keyword to use the ClassName... group heading for each class instance (and all the variables don't have the repeated ClassName.xxx). This is particularly useful together with a ClassComment for the class instances where the comment is shown in the group heading, displayed as: "ClassName (comment) ..."
|-
| <syntaxhighlight lang="pgm" inline> ClassAsPageLabel</syntaxhighlight>
| Keyword to display one class instance per tab page.
|-
| <syntaxhighlight lang="pgm" inline> ClassAsTextLabelLabel</syntaxhighlight>
| Keyword to display the class name as a text label heading to "separate" the class instances.
|-
|RowSpan = 5|Class Grid Display Formatting Keywords
| <syntaxhighlight lang="pgm" inline>ClassGrid Classes</syntaxhighlight>
|{{Available139|32530}} With the keyword '''ClassGrid''', class instances of user defined class types can be displayed in Grids (Tables) in the Access window with the class instances as columns. The ClassGrid keyword is used anywhere after class instances are declared to control where the grids are displayed. It is also possible to use the keyword when [[#Syntax_for_Declaring_Class_Instances|declaring the class instances]].
Where ''Classes'' is a list of class instances of the same class definition. ''Classes'' can be specified in a number of different methods such as using a previously defined ClassList or list of classes similar to [[#Classes_Parameter|Classes Parameter]] in ForEach macros. 
:Example (list of class instances): <syntaxhighlight lang="pgm" inline>ClassGrid {T1,T2,T3}</syntaxhighlight> (where ''T1,T2,T3'' are previously defined instances of the same class definition) 
:Example (ClassList): <syntaxhighlight lang="pgm" inline>ClassGrid L1</syntaxhighlight> (where ''L1'' is a previously defined [[#ClassList|ClassList]]) 
:Example (class definition type): <syntaxhighlight lang="pgm" inline>ClassGrid {TankClass}</syntaxhighlight> (where ''TankClass'' is a previously defined [[##Syntax_for_Class_Definition|Class Definition]]) 
:Example (class array): <syntaxhighlight lang="pgm" inline>ClassGrid Tanks</syntaxhighlight> (where ''Tanks'' is a previously defined [[#Syntax_for_Declaring_Class_Instances|Class Array]])

Notes:
* The width of each column can be controlled with the '''ClassGridColumnWidth''' keyword in the class definition.
* The maximum number of columns in a grid is controlled with the '''ClassGridMaxColumns''' keyword in the class definition. Additional grids are automatically created when there is a larger number of class instances.
* TextLabels within the class grid are shown as row separators, however blank lines and multiple text lines are ignored (only the last TextLabel in a sequence is shown). All text in a grid can be hidden if using keyword '''ClassGridHideText''' in the class definition.
* If comments are used for class instances, these are shown as text for each column in first row of grid. This can be disabled using keyword '''ClassGridHideComment''' in the class definition.
* If option ClassGridPageLabel is used in class definition, then the grid is displayed on a new tab page in the Access window.
* The use of ClassGrid allows positioning of display of the grid in Access window to be at any point after the declaration of class instances. To display the grid at the point of declaring the classes, use the {Grid} option or # symbol.
* Only user defined classes can be used in the ClassGrid. Predefined PGM class types (TagSelect, Matrix, etc.) cannot be used with ClassGrid.
* A class instance can only be displayed once in a grid.
|-
| <syntaxhighlight lang="pgm" inline>ClassGridColumnWidth Width</syntaxhighlight>
|Use this to change the default width (14) of each column displayed in a class grid.
|-
| <syntaxhighlight lang="pgm" inline>ClassGridMaxColumns MaxColumns</syntaxhighlight>
|Use this to change the maximum number of columns (10) allowed before a new grid is automatically created.
|-
|<syntaxhighlight lang="pgm" inline>ClassGridHideComment</syntaxhighlight>
|Use this to hide the display of class instance comments, that are normally displayed in the first row of the grid.
|-
|<syntaxhighlight lang="pgm" inline>ClassGridHideText</syntaxhighlight>
|Use this to hide the display of all TextLabels shown as text between rows in the grid.
|}

=== Examples of Grid Dsiplay Options ===

{|
|Valign=top Width=35% rowspan=3|
<syntaxhighlight lang="pgm">
;Class PGM
Class TankClass
;ClassAsPageLabel
;ClassAsTextLabel
;ClassAsGroup
;ClassGridColumnWidth 8 ;default is 14
;ClassGridMaxColumns 3 ;default is 10
;other code here....
String UnitTag{Tag}@
Real Volume*<<100>>("Vol", "m^3")
Real Height*<<1>>("L", "m")
Real ResidenceTime*("Time", "h")
TextLabel()
EndClass

;Main PGM
PageLabel("Tanks")
TextLabel(,)
TankClass Tank1, Tank2
;TankClass Tank[7]
;ClassGrid TankClass
;ExcludeWatch Tank[0]
;ExcludeClass Tank[0]
$</syntaxhighlight>

NOTE: The examples presented to the right uses different options from the above code (currently marked with ;).

|Valign=top|[[image:PGM_ClassDisplay.png|thumb|Using PageLabel keyword only]]
|Valign=top|[[image:PGM_ClassAsPageLabel.png|thumb|Using ClassAsPageLabel]]
|-
|Valign=top|[[image:PGM_ClassAsTextLabel.png|thumb|Using ClassAsTextLabel]]
|Valign=top|[[image:PGM_Classgroup.png|thumb|Using ClassAsGroup]]
|-
|Valign=top|[[image:PGM_ClassGrid.png|thumb|Using ClassGrid]]
|Valign=top|[[image:PGM_ClassGrid2.png|thumb|Using ClassGrid with custom width]]
|}

Class - Using a Class

2025-04-04T00:07:59Z

Eleanor.McFeaters: /* Syntax for Instance Definition */

2025-03-31T22:26:57Z

Eleanor.McFeaters: /* Class Macros */

Class - Macros

2025-03-31T22:13:09Z

Eleanor.McFeaters: /* Class Macros */