channel

A channel is the Tcl I/O model for character streams.

[why are channels important to the tcl programmer?]

[how are channels different from other constructs in tcl?]

[how do I create/use/destroy a channel?]

Tcl Features

stacked channel

a channel whose input or output is to/from another channel

reflected channel

a channel that is implemented at the script level

transform

describes the behaviour and interface of a stackable channel

virtual channel

an umbrella term for a channel implemented as a reflected channel and/or a stacked channel

Commands

chan

new in Tcl/Tk 8.5

close

eof

fblocked

fconfigure

fcopy

fileevent

flush

gets

puts

read

socket

tell

Half Bakery: Configurable Atom Type

PYK 2014-05-17: Tcl's channel mechanism currently only supports one type of atom: the byte. Could it be generalized to support arbitrary atom types? This could be put to use anywhere messages a passed, from flow-based programming to (gasp) UDP implementations. Hypothetical usage:

set chan [open {some resource descriptor}]
chan configure $chan -atom rfc2822
set msg [read $chan]
$msg headers

Yes, read would in this case construct new commands -- groovy eh?

See Also

Channel Implementations

enumerates all known channels, including those in extensions

Cplusplus streams and Tcl channels

The Tcl I/O system as seen by a driver (channel type)