eof - Check for end of file condition on channel
eof channelId
Returns 1 if an end of file condition occurred during the most recent input operation on channelId (such as gets), 0 otherwise.
ChannelId must be an identifier for an open channel such as a Tcl standard channel (stdin, stdout, or stderr), the return value from an invocation of open or socket, or the result of a channel creation command provided by a Tcl extension.
eof is, in one sense, a command:
http://purl.org/tcl/home/man/tcl8.4/TclCmd/eof.htm
and, in another sense, an acronym for End Of File.
Programmers can use eof to determine whether the channel has reached the end of input.
Note that it fires only after the last successful gets, so testing for a -1 return value on gets may be a better idea, and avoid eof's FMM [L1 ] by coding:
while {[gets $fp line]>=0} {...}instead of
while {![eof $fp]} {
gets $fp line
if [eof $fp break] ;# otherwise loops one time too many
...
} ;# RS Hmmm... the only thing I find eof good for is as a condition which should trigger closing a socket.
That is, if you are trying to read a non-blocking socket and you hit eof, you KNOW that it's time to close the socket.
-PSE
Can anyone indicate whether there are certain types of channels (pipe, socket, etc.) where eof doesn't do what one might at first blush expect?
JMN 2003-07-15 This isn't directly referring to the eof command - but is an EOF issue that I wasn't expecting so here looks as good a place as any to mention it.
Using the Memchan package, I was trying to fcopy from a memchan to a file roughly like so:
set m [memchan]
puts $m "someStringData"
seek $m 0 start
fcopy $m $fd -command CopyFinished
proc CopyFinished args { ... }This performed the copy to file just fine, but the CopyFinished proc never got called. To fix this, I called
fconfigure $m -eofchar {}before the puts line.. and
fconfigure $m -eofchar \x1a
before the fcopy line. Then I changed the puts line to:
puts $m "someStringData\x1a"
This seems like a bit of hoop-jumping to get the expected fcopy behaviour.. am I missing something simple?
Tcl syntax help - Arts and Crafts of Tcl-Tk Programming - Category Command - ]Category Introspection]