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2memchan(n)                                                          memchan(n)
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NAME

7       memchan - Create and manipulate memory channels
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SYNOPSIS

10       package require Tcl
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12       package require memchan
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14       memchan ?-initial-size len?
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DESCRIPTION

18       This  manpage  documents  both the overall package and the command mem‐
19       chan. The package itself provides a number of in-memory channels  which
20       can utilized to
21
22       ·      capture  stream-like  information  in  a  natural way instead of
23              using set and append to manipulate strings
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25       ·      or to transfer data between interpreters, in the same thread  or
26              not.
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COMMAND

29       memchan ?-initial-size len?
30              creates  a chunk-oriented in-memory channel and returns its han‐
31              dle. If an initial size is specified the system  will  pre-allo‐
32              cate  len  bytes  of  buffer  space for the contents. This is no
33              restriction on the ultimate size of the channel, it will  always
34              grow as much as is necessary to accomodate the data written into
35              it.
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37              The channels created here can be transfered between interpreters
38              in  the same thread and between threads, but only as a whole. It
39              is not possible to use them to create a  bi-  or  unidirectional
40              connection between two interpreters.
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42       Memory  channels created by memchan provide two read-only options which
43       can be queried via the standard fconfigure command. These are
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45       -length
46              The value of this option is the number of bytes currently stored
47              in the queried memory channel.
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49       -allocated
50              The  value of this option is the number of bytes currently allo‐
51              cated by the queried memory channel. This number is at least  as
52              big as the value of -length.
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54       As  the channels generated by memchan grow as necessary they are always
55       writable. This means that a writable fileevent-handler will  fire  con‐
56       tinuously.
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58       The channels are also readable if they contain more than zero bytes and
59       the seek location is not and the end of the channel. Under these condi‐
60       tions a readable fileevent-handler will fire continuously.
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62       Note  that  writing  to  such a channel usually occurs at the end, thus
63       supressing readable events. This also means that  users  have  to  take
64       care  to seek the channel to a location before the end before trying to
65       read data back.
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SEE ALSO

68       fifo, fifo2, null, zero, random
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KEYWORDS

71       memchan, chunk, in-memory channel, channel, i/o
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74       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
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78Memory channels                       2.2                           memchan(n)
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