transfer::copy(3tcl) Data transfer facilities transfer::copy(3tcl)
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NAME
transfer::copy - Data transfer foundation
SYNOPSIS
package require Tcl 8.4
package require transfer::copy ?0.2?
transfer::copy::do chan|string data outchannel ?options...?
transfer::copy::chan channel outchannel ?options...?
transfer::copy::string string outchannel ?options...?
transfer::copy::doChan channel outchannel optvar
transfer::copy::doString string outchannel optvar
transfer::copy::options outchannel optionlist optvar
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DESCRIPTION
This package provides a number of commands for the asynchronous of in-
formation contained in either a string or channel. The main point of
this package is that the commands here provide a nicer callback API
than the builtin command fcopy, making the use of these facilities sim-
pler than the builtin.
API
transfer::copy::do chan|string data outchannel ?options...?
This command transfers the information in data to the outchan-
nel, according to the options. The type of the information in
data is determined by the first argument.
The options available to this command are the same as are avail-
able to the command transfer::copy::options, and explained
there.
chan The argument data contains the handle of a channel and
the actual infomration to transfer is read from that
channel.
string The argument data contains a string and this is the in-
formation to be transfered.
transfer::copy::chan channel outchannel ?options...?
This command is a shorter and more direct form for the command
transfer::copy::do chan.
transfer::copy::string string outchannel ?options...?
This command is a shorter and more direct form for the command
transfer::copy::do string.
transfer::copy::doChan channel outchannel optvar
This command is an alternate form of transfer::copy::chan which
reads its options out of the array variable named by optvar in-
stead of from a variable length argument list.
transfer::copy::doString string outchannel optvar
This command is an alternate form of transfer::copy::string
which reads its options out of the array variable named by opt-
var instead of from a variable length argument list.
transfer::copy::options outchannel optionlist optvar
This command is the option processor used by all the commands
above which read their options from a variable length argument
list. It first reads default settings from the channel handle
outchannel, then processes the list of options in optionlist, at
last stores the results in the array variable named by optvar.
The contents of that variable are in a format which is directly
understood by all the commands above which read their options
out of an array variable.
The recognized options are:
-blocksize int
This option specifies the size of the chunks to transfer
in one operation. It is optional and defaults to the
value of -buffersize as configured for the output chan-
nel.
If specified its value has to be an integer number
greater than zero.
-command commandprefix
This option specifies the completion callback of the op-
eration. This option has to be specified. An error will
be thrown if it is not, or if the empty list was speci-
fied as argument to it.
Its value has to be a command prefix, i.e. a list whose
first word is the command to execute, followed by words
containing fixed arguments. When the callback is invoked
one or two additional arguments are appended to the pre-
fix. The first argument is the number of bytes which were
transfered. The optional second argument is an error mes-
sage and added if and only if an error occured during the
the transfer.
-progress commandprefix
This option specifies the progress callback of the opera-
tion. It is optional and defaults to the empty list. This
last possibility signals that no feedback was asked for
and disabled it.
Its value has to be a command prefix, see above, -command
for a more detailed explanation. When the callback is in-
voked a single additional arguments is appended to the
prefix. This argument is the number of bytes which were
transfered so far.
-size int
This option specifies the number of bytes to read from
the input data and transfer. It is optional and defaults
to "Transfer everything". Its value has to be an integer
number and any value less than zero has the same meaning,
i.e. to transfer all available data. Any other value is
the amount of bytes to transfer.
All transfer commands will throw error an when their user
tries to transfer more data than is available in the in-
put. This happens immediately, before the transfer is ac-
tually started, should the input be a string. Otherwise
the, i.e. for a channel as input, the error is thrown the
moment the underflow condition is actually detected.
-encoding encodingname
-eofchar eofspec
-translation transspec
These options are the same as are recognized by the
builtin command fconfigure and provide the settings for
the output channel which are to be active during the
transfer, and only then. I.e. the settings of the output
channel before the transfer are saved, and restored at
the end of a transfer, regardless of its success or fail-
ure. None of these options are required, and they default
to the settings of the output channel if not specified.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain
bugs and other problems. Please report such in the category transfer
of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
also report any ideas for enhancements you may have for either package
and/or documentation.
When proposing code changes, please provide unified diffs, i.e the out-
put of diff -u.
Note further that attachments are strongly preferred over inlined
patches. Attachments can be made by going to the Edit form of the
ticket immediately after its creation, and then using the left-most
button in the secondary navigation bar.
KEYWORDS
channel, copy, transfer
CATEGORY
Transfer module
COPYRIGHT
Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>
tcllib 0.2 transfer::copy(3tcl)