BOOPSI - Object Oriented Intuition - Revision history

Costel Mincea: Text replacement - "" to ""

2025-01-26T19:21:46Z

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Steven Solie: /* OOP Overview */

2017-12-05T19:47:53Z

OOP Overview

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	Following the branches upward from class to superclass will bring you to a universal root category from which all objects are derived. The OOP language ''Smalltalk'' calls this class "Object".		Following the branches upward from class to superclass will bring you to a universal root category from which all objects are derived. The OOP language ''Smalltalk'' calls this class "Object".

			[[File:ClassDiagram.png\|frame\|center\|Class Diagram]]
	<center>
	<classdiagram type="orderly" scale="80" dir="bt">
	[animal]-[object]
	[dog]-[animal]
	[cat]-[animal]
	[mouse]-[animal]
	[vegetable]-[object]
	[peas]-[vegetable]
	[corn]-[vegetable]
	[spinach]-[vegetable]
	</classdiagram>
	</center>

	<center>Object Diagram</center>

	Like ''Smalltalk'', BOOPSI also has a universal root catagory, ''rootclass''. Currently, Intuition defines three immediate subclasses of rootclass. The first, ''gadgetclass'', is the class of BOOPSI gadgets. The second class, ''imageclass'', makes up the class of BOOPSI images.		Like ''Smalltalk'', BOOPSI also has a universal root catagory, ''rootclass''. Currently, Intuition defines three immediate subclasses of rootclass. The first, ''gadgetclass'', is the class of BOOPSI gadgets. The second class, ''imageclass'', makes up the class of BOOPSI images.

Steven Solie: /* Creating a BOOPSI Class */

2015-11-04T17:51:28Z

Creating a BOOPSI Class

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	== Creating a BOOPSI Class ==		== Creating a BOOPSI Class ==

	So far this ~~chapter~~ has only hinted at what is possible with BOOPSI. Its power lies in its extensibility. BOOPSI grants the application programmer the power to add custom features to existing classes. If an existing class comes close to your needs, you can build on that class so it does exactly what you want. If you want a class that is unlike an existing class, you can create it.		So far this article has only hinted at what is possible with BOOPSI. Its power lies in its extensibility. BOOPSI grants the application programmer the power to add custom features to existing classes. If an existing class comes close to your needs, you can build on that class so it does exactly what you want. If you want a class that is unlike an existing class, you can create it.

	The heart of a BOOPSI class is its method ''Dispatcher'' function. According to the OOP metaphor, when an application wants a BOOPSI object to perform a method, it sends the object a message. In reality, that object is only a data structure, so it does not have the power to do anything. When an object receives a BOOPSI message, a BOOPSI message structure is passed to the dispatcher of that object's class. The dispatcher examines the message and figures out what to do about it.		The heart of a BOOPSI class is its method ''Dispatcher'' function. According to the OOP metaphor, when an application wants a BOOPSI object to perform a method, it sends the object a message. In reality, that object is only a data structure, so it does not have the power to do anything. When an object receives a BOOPSI message, a BOOPSI message structure is passed to the dispatcher of that object's class. The dispatcher examines the message and figures out what to do about it.

Steven Solie: /* Creating an Object */

2015-11-04T17:51:08Z

Creating an Object

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	In general, BOOPSI objects are "black boxes". This means the inner workings of BOOPSI objects are not visible to the application programmer, so the programmer does not know what goes on inside it. This really means the inner workings of these objects are none of your business. Unless otherwise documented, only use an object pointer as a handle to the object.		In general, BOOPSI objects are "black boxes". This means the inner workings of BOOPSI objects are not visible to the application programmer, so the programmer does not know what goes on inside it. This really means the inner workings of these objects are none of your business. Unless otherwise documented, only use an object pointer as a handle to the object.

	To create an object, '''NewObjectA()''' needs to know what class the new object is an instance of. To create a public class object, pass a NULL pointer in '''privclass''' and an ASCII string in '''pubclass''' naming the object's public class. The '''privclass''' pointer is used to create a private class object, which is covered in ~~the "~~Creating a BOOPSI Class" ~~section~~ ~~later in~~ ~~this chapter~~.		To create an object, '''NewObjectA()''' needs to know what class the new object is an instance of. To create a public class object, pass a NULL pointer in '''privclass''' and an ASCII string in '''pubclass''' naming the object's public class. The '''privclass''' pointer is used to create a private class object, which is covered in [[#Creating a BOOPSI Class\|Creating a BOOPSI Class]].

	The '''myattrs''' tag list is a list of tag/value pairs, each of which contains an initial value for some object attribute. Most objects have attributes which define the characteristics of the object to be created and used which are set by using specifically named tags. Many of these attributes of BOOPSI gagdets and images are derived from the old Intuition '''Gadget''' and '''Image''' structures (position, size, etc).		The '''myattrs''' tag list is a list of tag/value pairs, each of which contains an initial value for some object attribute. Most objects have attributes which define the characteristics of the object to be created and used which are set by using specifically named tags. Many of these attributes of BOOPSI gagdets and images are derived from the old Intuition '''Gadget''' and '''Image''' structures (position, size, etc).

Steven Solie: /* The Interconnection Classes */

2015-11-04T17:50:24Z

The Interconnection Classes

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	Icclass has a subclass called ''modelclass''. Using a modelclass object, an application can chain a series of these objects together to set up a "broadcast list" of icclass objects. The modelclass object is similar to the icclass object in that it has its own ICA_TARGET and ICA_MAP. It differs in that an application can use the modelclass OM_ADDMEMBER method to add icclass objects to the modelclass object's broadcast list.		Icclass has a subclass called ''modelclass''. Using a modelclass object, an application can chain a series of these objects together to set up a "broadcast list" of icclass objects. The modelclass object is similar to the icclass object in that it has its own ICA_TARGET and ICA_MAP. It differs in that an application can use the modelclass OM_ADDMEMBER method to add icclass objects to the modelclass object's broadcast list.

	The OM_ADDMEMBER method is defined by rootclass. It adds one BOOPSI object to the personal list of another BOOPSI object. It is up to the BOOPSI object's class to determine the purpose of the objects in the list. Unlike the other methods mentioned so far in this ~~chapter~~, OM_ADDMEMBER does not have an Intuition function equivalent. To pass an OM_ADDMEMBER message to an object use the function IDoMethodA(), or its stack-based equivalent, IDoMethod().		The OM_ADDMEMBER method is defined by rootclass. It adds one BOOPSI object to the personal list of another BOOPSI object. It is up to the BOOPSI object's class to determine the purpose of the objects in the list. Unlike the other methods mentioned so far in this article, OM_ADDMEMBER does not have an Intuition function equivalent. To pass an OM_ADDMEMBER message to an object use the function IDoMethodA(), or its stack-based equivalent, IDoMethod().

	The message that the OM_ADDMEMBER method uses looks like this (from <intuition/classusr.h>):		The message that the OM_ADDMEMBER method uses looks like this (from <intuition/classusr.h>):

Paul Sadlik: /* Simple BOOPSI Objects */

2013-05-27T21:00:44Z

Simple BOOPSI Objects

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	For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].		For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].

	==== Simple BOOPSI Objects ====		==== Creating and Using Simple BOOPSI Objects ====

	~~At the~~ following link ~~you~~ ~~can see~~ how to create, interact with ~~and dispose of~~ a simple BOOPSI object - system ~~requesters~~. ~~See~~ [[BOOPSI_101\|BOOPSI 101]].		The following link will explore how to create and interact with a simple BOOPSI object - a system requester. This section explains and provide code samples for the basic steps to create a new object, send the object messages, to adjust and read object attributes and to dispose of the object. Finally an example program is provided to fully demonstrate using the requester class. Please see [[BOOPSI_101\|BOOPSI 101]].

	==== Creating an Object ====		==== Creating an Object ====

Steven Solie at 18:59, 13 May 2013

2013-05-13T18:59:13Z

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	# The more commonly used second method relies on a variable length "stack" of tags that are defined within the function call. This method skips the code needed to declare / allocate a TagList. The name of functions using the "stack" tags method may end with "Tags" or omit the "A" suffix (mentioned above), like '''OpenWindowTags()''' or '''NewObject()'''.		# The more commonly used second method relies on a variable length "stack" of tags that are defined within the function call. This method skips the code needed to declare / allocate a TagList. The name of functions using the "stack" tags method may end with "Tags" or omit the "A" suffix (mentioned above), like '''OpenWindowTags()''' or '''NewObject()'''.

	Note, every tag list must end (or be "terminated") with a ~~TAG_DONE~~ tag. These tag lists can also contain utility.library Global System control tags (like TAG_SKIP), which BOOPSI uses in processing its tag lists. Any application that ends up processing these lists should do so using the tag manipulation functions from utility.library.		Note, every tag list must end (or be "terminated") with a TAG_END tag. These tag lists can also contain utility.library Global System control tags (like TAG_SKIP), which BOOPSI uses in processing its tag lists. Any application that ends up processing these lists should do so using the tag manipulation functions from utility.library.

	For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].		For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].
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	tt[0].ti_Tag = RKMMOD_CurrVal; /* make a tag list. */		tt[0].ti_Tag = RKMMOD_CurrVal; /* make a tag list. */
	tt[0].ti_Data = mmd->currval;		tt[0].ti_Data = mmd->currval;
	tt[1].ti_Tag = ~~TAG_DONE~~;		tt[1].ti_Tag = TAG_END;
	/* If the RKMMOD_CurrVal changes, we want everyone to know about */		/* If the RKMMOD_CurrVal changes, we want everyone to know about */
	IIntuition->IDoSuperMethod(cl, o, /* it. Theoretically, the class is supposed to send itself a */		IIntuition->IDoSuperMethod(cl, o, /* it. Theoretically, the class is supposed to send itself a */

Paul Sadlik: /* Using BOOPSI */

2013-05-12T22:15:32Z

Using BOOPSI

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	For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].		For more information on tags, see [[Utility_Library#Tags\|Utility Library - Tags]].

			==== Simple BOOPSI Objects ====

			At the following link you can see how to create, interact with and dispose of a simple BOOPSI object - system requesters. See [[BOOPSI_101\|BOOPSI 101]].

	==== Creating an Object ====		==== Creating an Object ====

Paul Sadlik: /* Setting an Existing Object's Attributes */

2013-05-12T20:41:09Z

Setting an Existing Object's Attributes

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	==== Setting an Existing Object's Attributes ====		==== Setting an Existing Object's Attributes ====

	An object's attributes are not necessarily static. An application can ask an object to set certain object attributes using the SetAttrs() function:		An object's attributes are not necessarily static. An application can ask an object to set certain object attributes using the '''SetAttrs()''' function:

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	Because BOOPSI gadgets require some extra information about their display, they use a special version of this function, SetGadgetAttrs():		Because BOOPSI gadgets require some extra information about their display, they use a special version of this function, '''SetGadgetAttrs()''':

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	Here myobject is a pointer to the BOOPSI object, w points to the gadget's window, r points to the gadget's requester, and the tag/value pairs are the attributes and their new values. The return value of SetAttrs() and SetGadgetAttrs() is class specific. In general, if the attribute change causes a visual change to some object, the SetAttrs()/SetGadgetAttrs() function should return a non-zero value, otherwise, these functions should return zero (see the [[BOOPSI_Class_Reference\|BOOPSI Class Reference]] for information on the return values for specific classes). The following is an example of how to set the current integer value and gadget ID of the gadget created in the NewObject() call above:		Here myobject is a pointer to the BOOPSI object, '''w''' points to the gadget's window, '''r''' points to the gadget's requester, and the tag/value pairs are the attributes and their new values. The return value of '''SetAttrs()''' and '''SetGadgetAttrs()''' is class specific. In general, if the attribute change causes a visual change to some object, the '''SetAttrs()''' / '''SetGadgetAttrs()''' function should return a non-zero value, otherwise, these functions should return zero (see the [[BOOPSI_Class_Reference\|BOOPSI Class Reference]] for information on the return values for specific classes). The following is an example of how to set the current integer value and gadget ID of the gadget created in the '''NewObject()''' call above:

	<syntaxhighlight>		<syntaxhighlight>
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	</syntaxhighlight>		</syntaxhighlight>

	This changes two of mystringgadget's attributes. It changes the gadget's current integer value to 75 and it changes the gadget's ID number to 2.		This changes two of '''mystringgadget''' 's attributes. It changes the gadget's current integer value to 75 and it changes the gadget's ID number to 2.

	Note that it is not OK to call SetGadgetAttrs() on a BOOPSI object that isn't a gadget, nor is it OK to call SetAttrs() on a BOOPSI gadget.		Note that it is not OK to call '''SetGadgetAttrs()''' on a BOOPSI object that isn't a gadget, nor is it OK to call '''SetAttrs()''' on a BOOPSI gadget.

	Not all object attributes can be set with SetGadgetAttrs()/SetAttrs(). Some classes are set up so that applications cannot change certain attributes. For example, the imagery for the knob of a proportional gadget cannot be altered after the object has been created. Whether or not a specific attribute is "settable" is class dependent. For more information about the attributes of specific classes, see the [[BOOPSI_Class_Reference\|BOOPSI Class Reference]].		Not all object attributes can be set with '''SetGadgetAttrs()''' / '''SetAttrs()'''. Some classes are set up so that applications cannot change certain attributes. For example, the imagery for the knob of a proportional gadget cannot be altered after the object has been created. Whether or not a specific attribute is "settable" is class dependent. For more information about the attributes of specific classes, see the [[BOOPSI_Class_Reference\|BOOPSI Class Reference]].

	==== Getting an Object's Attributes ====		==== Getting an Object's Attributes ====

Paul Sadlik: /* BOOPSI and Tags */

2013-05-12T20:29:08Z

BOOPSI and Tags

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	BOOPSI uses tag lists to pass and manipulate its attributes. To BOOPSI, each TagItem (defined in <utility/tagitem.h>) in a tag list is an attribute/value pair. The TagItem.ti_Tag field contains an ID for the attribute and the ti_Data field holds the attribute's value.		BOOPSI uses tag lists to pass and manipulate its attributes. To BOOPSI, each TagItem (defined in <utility/tagitem.h>) in a tag list is an attribute/value pair. The TagItem.ti_Tag field contains an ID for the attribute and the ti_Data field holds the attribute's value.

	For example, the string gadget class defines an attribute called '''STRINGA_LongVal''', which is the current integer value of the gadget. Certain gadgetclass objects have an attribute called '''GA_Image'''. Its value is not an integer, it is a pointer to an image. All of the attributes tags used by BOOPSI objects are documented in the ~~autodocs~~ on ~~those objects~~ - their ID's and possible values. In many cases attributes also have default values that are automatically used by an object, if those values are acceptable then you don't have to define those tags.		For example, the string gadget class defines an attribute called '''STRINGA_LongVal''', which is the current integer value of the gadget. Certain gadgetclass objects have an attribute called '''GA_Image'''. Its value is not an integer, it is a pointer to an image. All of the attributes tags used by BOOPSI objects are documented in the [[BOOPSI_Class_Reference\|BOOPSI Class Reference]] - their ID's and possible values. In many cases attributes also have default values that are automatically used by an object, if those values are acceptable then you don't have to define those tags.

	As is common with functions using tags, many BOOPSI functions typically have two variants reflecting the two methods of passing tagged attributes:		As is common with functions using tags, many BOOPSI functions typically have two variants reflecting the two methods of passing tagged attributes: