after 0 [list coroutine c1 apply [list {} {
	variable done
	set chan [chan create r {apply {{cmd chan args} {
	    switch $cmd {
		blocking - finalize {
		}
		watch {
		    chan postevent $chan read 
		}
		initialize {
		    list initialize finalize watch read write configure blocking
		}
		default {
		    error [list {unexpected command} $cmd]
		}
	    }
	}}}]
	chan configure $chan -blocking 0
	while 1 {
	    chan event $chan readable [list [info coroutine]]
	    yield
	    close $chan
	    set done 1
	    return
	}
    } [namespace current]]]
    vwait [namespace current]::done
return success
} success 



test io-29.1 {Tcl_WriteChars, channel not writable} {
    list [catch {puts stdin hello} msg] $msg
} {1 {channel "stdin" wasn't opened for writing}}
test io-29.2 {Tcl_WriteChars, empty string} {