Re: Convert Text to Variable Name
Re: Convert Text to Variable Name
- Subject: Re: Convert Text to Variable Name
- From: David Jacopille <email@hidden>
- Date: Sat, 15 Jan 2011 01:32:42 -0500
On Jan 14, 2011, at 7:57 PM, Mark J. Reed wrote: The principal problem is that these script objects can't access
variables from the surrounding context. If they could, then this
would work:
set myVar to 1
set varName to "myVar"
set varValue to (run script varName)
But instead you get this:
55:73: execution error: The variable myVar is not defined. (-2753)
Mark is right - scope is the problem. myVar is outside the scope of the script inside the "run script".
The solution is to pack BOTH the variable name and value together, and then evaluate them together inside the scope of the "run script".
This can be done in several ways. Here the first line is effectively combining line 1 and 2 from Mark's script into string that holds a record which holds both the variable name and value as a string. Scope is not an issue because both parts of myVar are in the string.
set myRecordAsString to "{myVar:1}"
eval(myRecordAsString) of me
on eval(superString) set myRecord to run script superString return myVar of myRecord end eval
Now that probably isn't exactly what you wanted because "myVar" is never a string by itself that can literally be converted into a variable name. Here's something that looks a lot closer:
property allMyVariables : "{myVar:1, yourVar:8, myHome:\"" & (path to home folder) & "\"}" on evalVar(variableName) return run script "return " & variableName & " of " & allMyVariables end evalVar
display dialog evalVar("myVar") -- displays 1 display dialog evalVar("myHome") -- displays the path to your home folder
evalVar converts text into real variable name, retrieves that variable's value, and can assign (or display) the value in one line, seemingly without scope problems. The scope problem are there, and are solved in the same way. We've just swept them under the carpet a bit further.
Dave
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