cvo - Label a dictionary for usage as an object in oo-programming  
Synopsis:dict cvo -> dict
Parameters:The operator modfies its argument
Description:In SLI dictionaries are used to represent the elements of the
object oriented programming paradigm. This is natural because the key value
pairs can specify functions as well as other data. Certain SLI operators like
SetStatus and GetStatus take C++ objects like nodes and random number distributions
as arguments but also SLI dictionaries. This enables the same algorithms to operate
on C++ and SLI objects. In order to avoid confusion with dictionaries not intended
to be used as an object, some operators require the dictionary to be labeld as
an object. If the dictionary is not labeles an error is issued. The operator cvdict
removes the label; cvd is the inverse operator of cvo.
<< /c 0 /inc {/c c 1 add def} >> cvo dup << /c 3 >> SetStatus /c get --> 3

{<< /c 0 /inc {/c c 1 add def} >> << /c 3 >> SetStatus} stopped
{3 npop true} {false} ifelse --> true

Remarks:The labeling is done by inserting the key /__is_object with value true.
The dictionary is only recognized as labeled if the key exists and its value is
true. However, usage of this key is considered to be an implementation detail and
may change in future versions of SLI.

SeeAlso: Source: