4D v14.3

OB Is defined

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4D v14.3
OB Is defined

OB Is defined 


 

OB Is defined ( object {; property} ) -> Function result 
Parameter Type   Description
object  Object in Structured object
property  Text in If passed = property to check, if omitted = check object
Function result  Boolean in If property omitted: True if object is defined, otherwise False.
If property passed: True if property is defined, otherwise False

The OB Is defined command returns True if object or property is defined, and False otherwise.

object must have been created using the C_OBJECT command.

By default, if you omit the property parameter, the command checks whether the object is defined. An object is defined if its contents has been initialized. 

Note: An object can be defined but empty. To find out if an object is undefined or empty, use the OB Is empty command. 

If you pass the property parameter, the command checks whether this property exists in object. Note that the property parameter is case sensitive.

Syntax testing the initialization of an object:

 C_OBJECT($object)
 $def:=OB Is defined($object// $def=false since $object is not initialized
 
 OB SET($object;"Name";"Martin")
 OB REMOVE($object;"Name")
 $def2:=OB Is defined($object// $def2=true since $object is empty {} but has been initialized

Test for existence of a property:

 C_OBJECT($ref)
 OB SET($ref;"name";"smith";"age";42)
  //...
 If(OB Is defined($ref;"age"))
  //...
 End if

This test is equivalent to:

 If(OB Get type($Object;"name")#Is undefined)

 
PROPERTIES 

Product: 4D
Theme: Objects (Language)
Number: 1231

 
HISTORY 

New
Created: 4D v14

 
SEE ALSO 

OB Is empty

 
ARTICLE USAGE

4D Language Reference ( 4D v14 R2)
4D Language Reference ( 4D v14 R3)
4D Language Reference ( 4D v14.3)
4D Language Reference ( 4D v14 R4)