collection.copy( )

Home

4D v18

collection.copy( )

Description

The collection.copy( ) method returns a deep copy of the collection instance. Deep copy means that objects or collections within the original collection are duplicated and do not share any reference with the returned collection.

Notes:

This method does not modify the original collection.
If applied to a shared collection, copy( ) returns a regular (not shared) collection.

If the original collection contains pointer type values, by default the copy also contains the pointers. However, you can resolve pointers when copying by passing the ck resolve pointers constant in the resolvePtrs parameter. In this case, each pointer present in the collection is evaluated when copying and its dereferenced value is used.

Example

 C_COLLECTION($col)

 C_POINTER($p)

 $p:=->$what

 

 $col:=New collection

 $col.push(New object("alpha";"Hello";"num";1))

 $col.push(New object("beta";"You";"what";$p))

 

 $col2:=$col.copy()

 $col2[1].beta:="World!"

 ALERT($col[0].alpha+" "+$col2[1].beta) //displays "Hello World!"

 

 $what:="You!"

 $col3:=$col2.copy(ck resolve pointers)

 ALERT($col3[0].alpha+" "+$col3[1].what) //displays "Hello You!"