`Scope`

{With, Cast, Context}

 

See the English definition for �scope�.

 

All Names belong to a specific Context.  All Names have a scope defined by their containing Cast[�], or Context[�] structures.  Cast[�] is used to isolate Names from the containing Context.

 

SubstitutionNames are lexical devices with a scope defined syntactically in Context[�], Cast[�], With[�], Name[�], and If[�] structures.  SubstitutionNames are not proper Names; they are lexical devices for inserting values into Expressions.  Like the values assigned in With[�] constructions, the pseudo-names used by SubstitutionNames do not have assignments or definitions.  Once a Named form has been elicited, values are substituted into the elicited expression in the same way values are substituted into the body of a With[{v=val,�}, body] construction.

 

 

 

Rules, or �If[Type[_,  _PatternSet], �]� constructs, are simple scoped constructs for SubstitutionNames.  Rules are documented in the `Condition` Context.  But in the interest of thoroughness, the form below is documented here as a scoped construct.  If patrnSet is a PatternSet, then the most general Rule form is the following:

 

            If[Type[subNam, patrnSet], doIfMatch , doIfNotMatch]

 

If patrnSet matches, subNam is substituted throughout doIfMatch, and the evaluated result is returned.

If patrnSet does not match, subNam is substituted throughout doIfNotMatc, and the evaluated result is returned.

 

 

 

Everything is Named and Reckoned in some Context.

 

The only exception to this are values assigned in With[{�Name[_,_]�}, �withExpr�]  constructions. 

But the names defined in With[�] constructs are not variables; they are pseudo-names because they are not reassignable.

 

The Names declared in the first argument of a Cast[�] construction are installed in the Context where that construction was interpreted.  These declared Names are unaffected by the use of identical names in the surrounding Context.  The Cast[�] construction, use these Names during the  life of its process execution thread.  Assignments to matching Names, (outside of the Cast[�] construction, in the containing Context), are unaffected.

 

 

 

scope n.       

1.a Archaic.  That at which one aims or to which the mind directs its view; ultimate design; intention; object. 

   b Obs.  One who is sought or desired.

2.  Intent; import; --of a writing or discourse; also, subject matter; theme. Archaic.

3. Obs. a A target, butt, or mark to be shot at; hence a goal. 

     b Med.  A method of treatment. 

     c An act of license or excess.

4. a Room or opportunity for free outlook, aim, or action; amplitude of opportunity; free course or vent; liberty.

            Excuse me if I have given too much scope to the reflections which have arisen in my mind.                                               Burke

    b Space for freedom of movement; room; range; as, scope to spread their branches.

5. a Distance within which a missile carries; range; as, the scope of a bow. 

    b Obs. exc. Dial. A tract of land, esp. a wide tract. 

    c Length; extent; sweep; as, scope of cable.

6.a range or extent of view, intent, or mental activity.

            Intellectual cultivation of no moderate � scope.                  Hawthorne.                                       

b. The range within which an activity displays itself; as, the scope of Napoleon�s genius; also, the field to which a subject is limited; as, the scope of an art or a memoir.

Syn.  �See RANGE.

                                                                        [From Websters1949Unabridged.]

 

 

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by John Van Wie Bergamini.

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