1) Namespaces

Namespaces : Context

We need to create name spaces.

Namespaces are

• a labeled/named subset of identified/labeled content,
  • content can then be precisely identified with a compound identfier
  • the conjuction of the subset name and the content name.
• commonly structured as nested hierarchies to allow reuse of names in different contexts.
• typically employed for the purpose of grouping symbols and identifiers around a particular functionality
  • to avoid name collisions between multiple identifiers that share the same name.
• hierarchical, ie sets of namespaces can be nested within another namespace

Namespaces : Examples

In TDX

NAMESPACE $project

Puts anything following in the current project context

NAMESPACE $project:subComponent
OR
NAMESPACE subComponent

Puts everyting that follows into the project's subComponent namespace

NAMESPACE subComponent - $system:language
OR
NAMESPACE subComponent - language
OR
NAMESPACE subComponent - $dxlib:codelib

Puts everything that follows into the project's subComponent namespace AND incorporates the system defined "language" namespace contents accessible to the project.

NB.

The default namespace is $project and coresponds to the base directory of the current project.
The default namespace to be included is $system and coresponds to a file refererd to by the dxiner environment variable.
If any other $name is used, it coresponds to a system based environment variable containing a directory where the coresponding ".tdx" file can be found. The variable can consist of a selection of paths, separated by semi-colons.

In VDX

Namespaces : Semantics

Namespaces : Data Definition

To store namespaces we need a structure similar to that detailed below ... explaination of the notation

In TDX

NAMESPACE $project:tdx - $system:lang 
  // however $project is implied and not really needed

  SINGLETON design
    namespace ourNameSpaces = NEW namespace("system")

    SYNTAX
      textualDesignClause := ( designClause )+;
      designClause := namespaceClause ( designComponentClause )+;
      designComponentClause := ... ;

  CLASS namespace(ubyte$ name)
    namespace{} subSpaces
    
    namespace(namespace) addNamespace(newNameSpace) =
    {
      subSpaces->add(newNameSpace)
      RETURN newNameSpace
    }

    SYNTAX
        namespaceClause := "NAMESPACE" newNameSpaceClause 
          ( "-" ( existingNameClause )+ );
        newNameSpaceClause := ( "$" ident ( ":" ident )* | ident ( ":" ident )+ );
        existingNameClause := ( "$" ident ( ":" ident )* | ident ( ":" ident )+ );

In VDX

Namespaces : Syntax

INFORMATION MODEL

PROCEDURAL MODEL

(1.1) Data Types

(2) Types

(3) Enums

(4) Signals

(5) Singletons

(6) Classes

(7) Expression Syntax

(7.1) What about identifiers (Expression Syntax) ?

(7.2) Compile Time Type Checking