chan - Manipulate channels
http://purl.org/tcl/home/man/tcl8.5/TclCmd/chan.htm
chan option ?arg arg ...?
This command (introduced in Tcl 8.5) provides several operations on a channel, including many that have been available using a mix of other commands. Option indicates what to do with the channel. Any unique abbreviation for option is acceptable. The valid options are: (see complete man page; here's only notes on selected options).
Why was thing thing called 'chan' instead of 'channel'? schlenk: It's mentioned in the TIP [L1 ], basically same style as interp for interpreter.
I see. Thank you for pointing that out. Pretty lame reasoning when "channel" is much more descriptive. But I'm not the one doing all the work so I'm not complaining!
JYL If you dont like chan you can do 'interp alias {} channel {} chan'
AMG: chan aggregates all the commands you'll need for working with chan blocked channelId - like fblocked
chan close channelId - like close
chan configure channelId ?optionName? ?value? ?optionName value?... - like fconfigure
chan copy inputChan outputChan ?options...?
chan create mode cmdPrefix
chan event channelId event ?script? - like fileevent
chan flush channelId - like flush
chan gets channelId ?varName? - like gets
chan names ?globPattern? - like file channels
chan postevent channelId eventSpec
chan puts ?-nonewline? ?channelId? string - like puts
chan read channelId ?numChars? - like read
chan read ?-nonewline? channelId -like read
chan seek channelId offset ?origin? - like seek
chan tell channelId - like tell
chan truncate channelId ?length?
TIP 287 proposes a [chan available channelId] command to find out how much available input is currently being buffered that could be chan read in. (It would make it safe to use chan gets with sockets since you could introspect and detect someone sending an excessively long line rather than running out of memory first.)
See also chan mode for an example how to extend that ensemble.
RS History sometimes runs in circles... Tcl 2.1 didn't have commands dealing with channels. Peter da Silva added the "stream" extension, where one could write
stream fp open $filename r set x [stream fp gets] stream fp close
Later, the parts of "stream" went into the core as separate commands. Still later (in 8.5), they get reunited again in chan, which arguably makes the command set leaner, but scripts wordier...
[ Category Command of Tcl 8.5 | Category Channel ]