fblocked man page on QNX

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fblocked(n)		     Tcl Built-In Commands		   fblocked(n)

______________________________________________________________________________

NAME
       fblocked	 -  Test whether the last input operation exhausted all avail‐
       able input

SYNOPSIS
       fblocked channelId
_________________________________________________________________

DESCRIPTION
       The fblocked command returns 1 if the most recent  input	 operation  on
       channelId  returned  less information than requested because all avail‐
       able input was exhausted.  For example, if gets is invoked  when	 there
       are  only  three	 characters  available	for  input  and no end-of-line
       sequence, gets returns  an  empty  string  and  a  subsequent  call  to
       fblocked will return 1.

       ChannelId must be an identifier for an open channel such as a Tcl stan‐ │
       dard channel (stdin, stdout, or stderr), the return value from an invo‐ │
       cation  of  open or socket, or the result of a channel creation command │
       provided by a Tcl extension.

EXAMPLE
       The fblocked  command  is  particularly	useful	when  writing  network
       servers,	 as  it	 allows you to write your code in a line-by-line style
       without preventing the servicing of other  connections.	 This  can  be
       seen in this simple echo-service:

	      # This is called whenever a new client connects to the server
	      proc connect {chan host port} {
		  set clientName [format <%s:%d> $host $port]
		  puts "connection from $clientName"
		  fconfigure $chan -blocking 0 -buffering line
		  fileevent $chan readable [list echoLine $chan $clientName]
	      }

	      # This is called whenever either at least one byte of input
	      # data is available, or the channel was closed by the client.
	      proc echoLine {chan clientName} {
		  gets $chan line
		  if {[eof $chan]} {
		      puts "finishing connection from $clientName"
		      close $chan
		  } elseif {![fblocked $chan]} {
		      # Didn't block waiting for end-of-line
		      puts "$clientName - $line"
		      puts $chan $line
		  }
	      }

	      # Create the server socket and enter the event-loop to wait
	      # for incoming connections...
	      socket -server connect 12345
	      vwait forever

SEE ALSO
       gets(n), open(n), read(n), socket(n), Tcl_StandardChannels(3)

KEYWORDS
       blocking, nonblocking

Tcl				      7.5			   fblocked(n)
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