This prints var's value

proc reader {} {
    ::yield
}

oo::class create ::Lamb {
    method reader {} {
	::yield
	variable var
	puts stderr "Var: $var / [namespace current] / [namespace exists [namespace current]]"
    }

    constructor {} {
	variable var 1
	set ::ns [info object namespace [self]]
	::coroutine ::meh [self] reader	;# will crash
	#::coroutine ::meh reader	;# will not crash
    }
}

[::Lamb new] destroy
foreach o [info class instances ::Lamb] {
    catch {info object namespace $o} e eo
    puts "1: $e ($eo)"
}

puts stderr "NS: [namespace exists $ns]"
::meh die
puts stderr "NS: [namespace exists $ns]"

foreach o [info class instances ::Lamb] {
    catch {info object namespace $o} e eo
    puts "2: $e ($eo)"
}