Tcl/Tk 8.5 Programming Cookbook

Using the eval command

The eval command accepts one or more arguments that, when combined, create a Tcl script. When invoked, it passes the stored script to the command interpreter and behaves as a normal command, returning the values or errors that may have resulted.

Although the eval command is not an error handling construct in itself, it provides an elegant methodology for utilizing Tcl commands as variables themselves. This allows greater freedom for passing commands to procedures and constructs, for example the error handling constructs referenced here.

Getting ready

To complete the following example, we will need to access Tcl from the command line. Launch the Tcl shell appropriately for your operating system and follow the given instructions. ...