How to predefine Apple Script constants or variables - macos

Question

Is it possible to predefine constant or variable for an AppleScript in cocoa application?
in other words is the function "addConstantToAppleScript" (used in the following code) definable?
addConstantToAppleScript("myText", "Hello!");
char *src = "display dialog myText";
NSString *scriptSource = [NSString stringWithCString:src];
NSAppleScript *appleScript = [[NSAppleScript alloc] initWithSource:scriptSource];
NSDictionary *scriptError = [[NSDictionary alloc] init];
[appleScript executeAndReturnError:scriptError];
thanks.

Answer 1

If you want to prepend an NSDictionary of key/value pairs to the beginning of an NSString containing AppleScript you could use something like the following function. Personally I would do this as a category on NSString but you have asked for a function.
NSString *addConstantsToAppleScript(NSString *script, NSDictionary *constants) {
NSMutableString *constantsScript = [NSMutableString string];
for(NSString *name in constants) {
[constantsScript appendFormat:#"set %# to \"%#\"\n", name, [constants objectForKey:name]];
}
return [NSString stringWithFormat:#"%#%#", constantsScript, script];
}
This function converts the key/value pairs to AppleScript statements of the form set <key> to "<value>". These statements are then added to the front of the supplied script string. The resulting script string is then returned.
You would use the above function as follows:
// Create a dictionary with two entries:
// myText = Hello\rWorld!
// Foo = Bar
NSDictionary *constants = [[NSDictionary alloc ] initWithObjectsAndKeys:#"Hello\rWorld!", #"myText", #"Bar", #"Foo", nil];
// The AppleScript to have the constants prepended to
NSString *script = #"tell application \"Finder\" to display dialog myText";
// Add the constants to the beginning of the script
NSString *sourceScript = addConstantsToAppleScript(script, constants);
// sourceScript now equals
// set Foo to "Bar"
// set myText to "Hello\rWorld!"
// tell application "Finder" to display dialog myText
NSAppleScript *appleScript = [[NSAppleScript alloc] initWithSource:sourceScript];