IsHandle

Revision as of 18:41, 24 February 2009 by Lchrisman (talk | contribs) (→‎See Also)

New to Analytica 4.2

IsHandle( X, local)

IsHandle(X) tests whether the value in «X» is a handle. When «X» is array-valued, it tests whether each cell of the array contains a handle.

IsHandle(X,local:true) tests whether a local variable «X» contains a handle. This form doesn't resolve «X» to its value, and really the only way to tell whether a local variable is acting as an alias of another object. When «X» is something other than the name of a local variable, the optional local parameter has no effect.

Library

Special

Examples

For the examples, assume these global variables are defined as follows: 

Index I := [1,2,3,4]
Variable hI := Handle(I)
Variable B := Table(I)(0,Null,hI,Handle(hI))

IsHandle(I) → [0,0,0,0] indexed by I
IsHandle(hI) → 1
IsHandle(B) → [0,0,1,1] indexed by I
{ Note: local:true has no effect when «X» is not a local variable: }
IsHandle(I,local:true) → [0,0,0,0] indexed by I
IsHandle(hI,local:true) → 1
IsHandle(B,local:true) → [0,0,1,1] indexed by I

Var x := I Do IsHandle(x) → [0,0,0,0] indexed by I
Var x := I Do IsHandle(x,local:true) → 0
Var x := Handle(I) Do IsHandle(x) → [0,0,0,0] indexed by I
Var x := Handle(I) Do IsHandle(x,local:true) → 1
Var x := hI Do IsHandle(x) → [0,0,0,0] indexed by I
Var x := hI Do IsHandle(x,local:true) → 1
Var x := B Do IsHandle(x) → [0,0,1,1] indexed by I
Var x := B Do IsHandle(x,local:true) → 0

LocalAlias x := I Do IsHandle(x) → [0,0,0,0] indexed by I
LocalAlias x := I Do IsHandle(x,local:true) → 0
LocalAlias x := Handle(I) Do IsHandle(x) → [0,0,0,0] indexed by I
LocalAlias x := Handle(I) Do IsHandle(x,local:true) → 1
LocalAlias x := hI Do IsHandle(x) → [0,0,0,0] indexed by I
LocalAlias x := hI Do IsHandle(x,local:true) → 1
LocalAlias x := B Do IsHandle(x) → [0,0,1,1] indexed by I
LocalAlias x := B Do IsHandle(x,local:true) → 0

MetaVar x := I Do IsHandle(x) → [0,0,0,0] indexed by I
MetaVar x := I Do IsHandle(x,local:true) → 0
MetaVar x := Handle(I) Do IsHandle(x) → 1
MetaVar x := Handle(I) Do IsHandle(x,local:true) → 1
MetaVar x := hI Do IsHandle(x) → 1
MetaVar x := hI Do IsHandle(x,local:true) → 1
MetaVar x := B Do IsHandle(x) → [0,0,1,1] indexed by I
MetaVar x := B Do IsHandle(x,local:true) → 0

Index J := 1..5 Do IsHandle(J) → [0,0,0,0,0] indexed by J
Index J := 1..5 Do IsHandle(J,local:true) → 1
MetaIndex J := [0,Null,hI,Handle(I)] Do IsHandle(J) → [0,0,1,1] indexed by J
MetaIndex J := [0,Null,hI,Handle(I)] Do IsHandle(J,local:true) → 1

Function F(X:Variable) := IsHandle(X,local:true)  → 1 {always}
Function F(X:Object)   := IsHandle(X,local:true)  → 1 {always}

See Also

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