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"InactiveExpression" (Interpreter Type)

Wolfram Language expression.

Details

Allowed Forms

  • Any valid Wolfram Language expression.

Restriction Specifications

Interpretation

Examples

Basic Examples  (7)

Interpret expressions and avoid evaluation:

Wolfram Language code: Interpreter["InactiveExpression"]["Sin[Pi/2]"]
Wolfram Language code: Interpreter["InactiveExpression"]["3+2"]

No evaluation is attempted when matching the choices:

Wolfram Language code: Interpreter[Restricted["InactiveExpression", {{1, 2, 3, 4}}]]["2+1"]
Wolfram Language code: Interpreter[Restricted["InactiveExpression", {{2, Inactivate[2 + 1]}}]]["2+1"]

By default, only expressions with no side effect are allowed:

Wolfram Language code: Interpreter["InactiveExpression"]["Quit[]"]

This can be changed by allowing All symbols:

Wolfram Language code: Interpreter[Restricted["InactiveExpression", All]]["Quit[]"]

Restrict to a list of symbols:

Wolfram Language code: Interpreter[Restricted["InactiveExpression", {Map, List, Function, Slot}]]["#&/@{1,2,3}"]
Wolfram Language code: Interpreter[Restricted["InactiveExpression", {Map, List, Function, Slot}]]["#+1&/@{1,2,3}"]

By default, new symbols are created in $Context, but a custom context can be specified:

Wolfram Language code: var = Interpreter[Restricted["InactiveExpression", Automatic, Automatic, Automatic]]["x"] Context[Evaluate[var]]
Wolfram Language code: var = Interpreter[Restricted["InactiveExpression", Automatic, Automatic, "mycontext`"]]["x"] Context[Evaluate[var]]

Specify contexts for the allowed and output symbols:

Wolfram Language code: mycontext`x = 10; Interpreter[Restricted["InactiveExpression", Automatic, {"mycontext`", "System`"}, "mycontext`"]]["y = x + 1"]

Prevent the creation of any new symbol:

Wolfram Language code: Interpreter[Restricted["InactiveExpression", Automatic, Automatic, None]]["3+1"]
Wolfram Language code: Interpreter[Restricted["InactiveExpression", Automatic, Automatic, None]]["z+1"]