ObjectOrientedProgramming

general
   NULLobject     external       objectvar      this           
   begintemplate  init           objref         unref          
   endtemplate    new            public
See Object Oriented Programming in the reference manual.

begintemplate

ObjectOrientedProgramming

SYNTAX

begintemplate

DESCRIPTION

Declare a new class or data structure. Any HOC code may appear between the begintemplate and endtemplate declarations. Classes are instantiated with the new statement.

EXAMPLES

begintemplate String
public s
strdef s
 proc init() {
   if (numarg()) {
     s = $s1
   }
 }
endtemplate String
objref s
s = new String("Hello")
print s.s
will print "Hello" to the screen.

endtemplate

ObjectOrientedProgramming

SYNTAX

endtemplate

DESCRIPTION

Closes the class declaration

SEE ALSO

begintemplate

objectvar

ObjectOrientedProgramming

SYNTAX

objectvar

DESCRIPTION

Synonym for objref .

objref

ObjectOrientedProgramming

SYNTAX

objref

DESCRIPTION

A comma separated list declarations of object variables. Object variables are labels (pointers, references) to the actual objects. Thus o1 = o2 merely states that o1 and o2 are labels for the same object. Objects are created with the new statement. When there are no labels for an object the object is deleted. The keywords objectvar and objref are synonyms.

An object has a unique name that can be determined with the print obj statement and consists of the template name followed by an index number in brackets. This name can be used in place of an objref.

EXAMPLES

objref vec, g
vec = new Vector(20)
g = new Graph()
creates a vector object and a graph object with pointers named vec and g, respectively.

SEE ALSO

new , begintemplate , List , pointprocesses , SectionList

public

ObjectOrientedProgramming

SYNTAX

public

DESCRIPTION

A comma separated list of all the names in a class that are available outside the class.

SEE ALSO

begintemplate

external

ObjectOrientedProgramming

SYNTAX

external

DESCRIPTION

A comma separated list of functions, procedures, iterators, objects, strings, or variables defined at the top level that can be executed within this class. This statement is optional but if it exists must follow the begintemplate or public line. This allows an object to get information from the outside and can be used as information shared by all instances. External iterators can only use local variables and arguments.

EXAMPLES

global_ra = 100
 func ra_value() {return global_ra}
begintemplate Cell
 external ra_value
 create axon
 proc init() {
	forall Ra = ra_value()	/* just the axon */
 }
endtemplate Cell

execute1 can be used to obtain external information as well.

new

ObjectOrientedProgramming

SYNTAX

objectvariable = new Object(args)

DESCRIPTION

Creates a new object/instance of type/class Object and makes objectvariable label/point to it. When the object no longer is pointed to, it no longer exists.

EXAMPLES

objref vec
vec = new Vector(30)
creates a vector of size 30 with its pointer named vec.

init

ObjectOrientedProgramming

SYNTAX

proc init() { ... }

DESCRIPTION

If an init procedure is defined in a template, then it is called whenever an instance of the template is created.

SEE ALSO

new

unref

ObjectOrientedProgramming

SYNTAX

proc unref() { print this, " refcount=", $1 }

DESCRIPTION

If an unref procedure is defined in a template, then it is called whenever the reference count of an object of that type is decremented. The reference count is passed as the argument. When the count is 0, the object will be destroyed on return from unref. This is useful in properly managing objects which mutually reference each other. Note that unref may be called recursively.

NULLobject

ObjectOrientedProgramming

SYNTAX

objref nil

DESCRIPTION

When an object variable is first declared, it refers to NULLobject until it has been associated with an instance of some object class by a new statement. A NULLobject object variable can be useful as an argument to certain class methods.

EXAMPLES

objref nil
print nil  // prints NULLobject

this

ObjectOrientedProgramming

SYNTAX

objref this

DESCRIPTION

Declared inside a template (see begintemplate ). Allows the object to call a procedure with itself as one of the arguments.

EXAMPLES

begintemplate Demothis
   public printname
   objref this

   proc init() {
     printname()
   }

   proc printname() {
     print "I am ", this
   }
endtemplate Demothis

objref foo[3]
print "at creation"
for i=0,2 foo[i]=new Demothis()
print "check existing"
for i=0,2 foo[i].printname()

neuron/general/oop.hel : May 13 2012