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authordkf <donal.k.fellows@manchester.ac.uk>2004-05-28 12:23:50 (GMT)
committerdkf <donal.k.fellows@manchester.ac.uk>2004-05-28 12:23:50 (GMT)
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diff --git a/doc/fblocked.n b/doc/fblocked.n
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--- a/doc/fblocked.n
+++ b/doc/fblocked.n
@@ -4,7 +4,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: fblocked.n,v 1.4 2001/09/14 19:20:40 andreas_kupries Exp $
+'\" RCS: @(#) $Id: fblocked.n,v 1.5 2004/05/28 12:23:50 dkf Exp $
.so man.macros
.TH fblocked n 7.5 Tcl "Tcl Built-In Commands"
.BS
@@ -31,9 +31,43 @@ Tcl standard channel (\fBstdin\fR, \fBstdout\fR, or \fBstderr\fR),
the return value from an invocation of \fBopen\fR or \fBsocket\fR, or
the result of a channel creation command provided by a Tcl extension.
.VE
+.SH EXAMPLE
+The \fBfblocked\fR 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:
+
+.CS
+# 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 {![\fBfblocked\fR $chan]} {
+ # Didn't block waiting for end-of-line
+ puts "$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
+.CE
.SH "SEE ALSO"
-gets(n), open(n), read(n), Tcl_StandardChannels(3)
+gets(n), open(n), read(n), socket(n), Tcl_StandardChannels(3)
.SH KEYWORDS
blocking, nonblocking