Purpose: discuss general guidelines for gathering input and then making use of it in Tcl.
A new user often finds s/he has a problem when dealing with user input.
Sometimes, the problem is a file name with a space in it. Sometimes, the problem is a string with special characters like [ or $ .
On this page, please add notes to help a new programmer avoid these problems.
One important thing is to keep the type of the input string in mind as you code. While Tcl has the reputation of everything is a string, not every command expects all its arguments to be arbitrary strings. In the most obvious example, Tcl input or output commands which require a file handle expects that argument to be a string returned from an open type command. Just handing some arbitrary string is very likely not going to work.
Similarly, handing an arbitrary string to a command which expects an argument in a list format may very well not work either.
[Perhaps a real example of this will eventually surface, replacing this commenet, since my last attempt failed so miserably...]