'''What's My Line?''' is a game-style exercise where the goal is to guess the
output of the Tcl script


** Description **

The following Tcl scripts are arranged in ascending order roughly according to
the level of challenge the pose.  The task is simple:  read a script, and then
guess what the output will be.   Actually writing down your answer before
looking at the answer is highly recommended.  When you get something wrong,
spend some time writing similar scripts in order to explore the subject in more
detail.

Size your browser window so that the answer is not visible while you form your
own answer. 


** Scripts **


*** No Soup For You ***

======
proc proc {args} {
    puts {No soup for you!}
}

proc hello {} {
    puts {Hi there!}
}

catch {hello} res
puts $res
======

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'''Answer:'''

======
No soup for you!
invalid command name "hello"
======

The built-in [[`[proc]`] is placed by a user-defined procedure that, instead of
creating new procedures, prints `No soup for you!`.  `proc hello...` then
doesn't create a `hello` procedure, so when an attempt is made to invoke
`hello`, no such command is found, and an error is produced instead.


*** Source in a [[`[proc]`] in a [[`[namespace]`] ***

Prior to running this script create a file named `data` that contains:

======none
#this file should be called "data"
set localvar 99
======

======
namespace eval ns1 {
    proc proc1 {} {
        upvar 0 [namespace current]::var1 localvar
        source data
        set var2 Hello
    }
    proc1
}

catch {set ns1::var1} eres einfo
puts $eres
catch {set ns1::var2} eres einfo
puts $eres
catch {set $var2} eres einfo
puts $eres
======

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'''answer:'''

======
99
can't read "ns1::var2": no such variable
can't read "var2": no such variable
======

[[`[source]`] causes a script to be evaluated in the current scope.



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