Re: invoked "break" outside of a loop
- From: Darren New <dnew@xxxxxxxxxx>
- Date: Sun, 24 Sep 2006 16:59:56 GMT
Russell Trleleaven wrote:
Sorry to belabor the point but I was hoping someone would explain why
"break"
"uplevel break"
and
"namespace eval :: break"
don't work like I thought they might.
As you've learned, [break] is simply a return with a special code attached. Hence, when you invoke [break], it invokes a command that returns that special code, which is caught inside your proc, which leads to the error. I.e., the proc is converting the return from [break] into a different type of return, since [break] is invoked several levels down the return stack from the [for] loop.
For example...
proc AA {} {
BB
puts "got here AA"
|
proc BB {} {
if {[catch {
uplevel "set x 0"
}]} { puts "caught something" }
puts "got here BB"
}
Now, given that [set x 0] there return no error, nothing prints.
Were the [set x 0] to be replaced with an error call, you would expect the catch to catch it, yes?
Hence, since [break] is simply a kind of error, that error return is returned to the caller for use in [catch]. Since there is no [catch], it propagates up to the environment of the proc, where proc is about to return, and says "Hey, why are you throwing a [break] without an appropriate [catch]?"
Does that help?
--
Darren New / San Diego, CA, USA (PST)
Just because you find out you are
telepathic, don't let it go to your head.
.
- References:
- invoked "break" outside of a loop
- From: Russell Trleleaven
- Re: invoked "break" outside of a loop
- From: Gerald W. Lester
- Re: invoked "break" outside of a loop
- From: Russell Trleleaven
- invoked "break" outside of a loop
- Prev by Date: Re: How to copy a proc
- Next by Date: Re: Expect for Windows NEWBIE question 'Broken pipe while executing' cisco router telnet script
- Previous by thread: Re: invoked "break" outside of a loop
- Next by thread: Freewrap6.2 and Snack 2.2
- Index(es):
Relevant Pages
|
|
