Evaluating Expressions at Runtime

Value Function

Behavior: Returns the value of its parameter evaluated as a SenseTalk expression. One use of this would be to accept text entered by a user that might contain an expression (such as "12.95 + 6%") and calculate its value. Another would be to read a file containing a list or property list and quickly convert it from the text format stored in the file into a useful collection of values.

The expression is evaluated in the context of the current handler. It may include variables (such as total in the second example above), operators, function calls, and so forth. If the evaluationContext property is set to Global or Universal, variables are treated as global or universal rather than local. If an error occurs while obtaining the value of the expression, the result function returns an exception object describing the problem.

Syntax:

value(expr){the} value of expr
ClosedReading Syntax Definitions

Syntax definitions for language elements follow these formatting guidelines:

  • boldface: Indicates words and characters that must be typed exactly
  • italic: Indicates expressions or other variable elements
  • {} (curly braces): Indicate optional elements.
  • [] (square brackets) separated by | (vertical pipes): Indicate alternative options where one or the other can be used, but not both.

Example syntax:

In this example, "open file" is required and must be typed exactly. "fileName" is a variable element; it is the path to and name of the file being opened. The following expression is optional and indicates why the file is being opened. If this expression is added, "for" is required and must be typed exactly. One of the following must be included, but only one, and they also must be typed exactly: "reading", "writing", "readwrite", "appending", or "updating".

open file fileName { for [reading | writing | readwrite | appending | updating] }
Note: SenseTalk is not case-sensitive.

Examples:

put the value of "51+93" into sum -- sets sum to 144

put value("total is greater than quarter" & bestQtrNum) into best

put value("(" & commaSeparatedText &")") into myList

put the value of file "storedProperties" into pList

Related:

 

This topic was last updated on August 19, 2021, at 03:30:51 PM.

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