source - Evaluate a file or resource as a Tcl script
source -rsrc resourceName ?fileName?
source -rsrcid resourceId ?fileName? _________________________________________________________________
This command takes the contents of the specified file or resource and passes it to the Tcl interpreter as a text script. The return value from source is the return value of the last command executed in the script. If an error occurs in evaluating the contents of the script then the source command will return that error. If a return command is invoked from within the script then the remainder of the file will be skipped and the source command will return normally with the result from the return command.
The -rsrc and -rsrcid forms of this command are only available on Macintosh computers. These versions of the command allow you to source a script from a TEXT resource. You may specify what TEXT resource to source by either name or id. By default Tcl searches all open resource files, which include the current application and any loaded C extensions. Alternatively, you may specify the fileName where the TEXT resource can be found.