[comment {-*- tcl -*- doctools manpage}]
[manpage_begin transfer::copy n 0.2]
[keywords channel]
[keywords copy]
[keywords transfer]
[copyright {2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>}]
[moddesc   {Data transfer facilities}]
[titledesc {Data transfer foundation}]
[category  {Transfer module}]
[require Tcl 8.4]
[require transfer::copy [opt 0.2]]
[description]
[para]

This package provides a number of commands for the asynchronous of
information 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 [cmd fcopy], making the use of these
facilities simpler than the builtin.

[section API]

[list_begin definitions]

[call [cmd transfer::copy::do] [const chan]|[const string] [arg data] \
	[arg outchannel] [opt [arg options]...]]

This command transfers the information in [arg data] to the
[arg outchannel], according to the [arg options]. The type of the
information in [arg data] is determined by the first argument.

[para]

The options available to this command are the same as are available to
the command [cmd transfer::copy::options], and explained there.

[list_begin definitions]
[def [const chan]]

The argument [arg data] contains the handle of a channel and the
actual infomration to transfer is read from that channel.

[def [const string]]

The argument [arg data] contains a string and this is the information
to be transfered.

[list_end]

[call [cmd transfer::copy::chan] [arg channel] [arg outchannel] \
	[opt [arg options]...]]

This command is a shorter and more direct form for the command
[cmd {transfer::copy::do chan}].

[call [cmd transfer::copy::string] [arg string] [arg outchannel] \
	[opt [arg options]...]]

This command is a shorter and more direct form for the command
[cmd {transfer::copy::do string}].

[call [cmd transfer::copy::doChan] [arg channel] [arg outchannel] \
	[arg optvar]]

This command is an alternate form of [cmd transfer::copy::chan] which
reads its options out of the array variable named by [arg optvar]
instead of from a variable length argument list.

[call [cmd transfer::copy::doString] [arg string] [arg outchannel] \
	[arg optvar]]

This command is an alternate form of [cmd transfer::copy::string] which
reads its options out of the array variable named by [arg optvar]
instead of from a variable length argument list.

[call [cmd transfer::copy::options] [arg outchannel] [arg optionlist] \
	[arg 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 [arg outchannel],
then processes the list of options in [arg optionlist], at last stores
the results in the array variable named by [arg 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.

[para]

The recognized options are:

[list_begin options]

[opt_def -blocksize [arg int]]

This option specifies the size of the chunks to transfer in one
operation. It is optional and defaults to the value of
[option -buffersize] as configured for the output channel.

[para]
If specified its value has to be an integer number greater than zero.

[opt_def -command [arg commandprefix]]

This option specifies the completion callback of the operation. This
option has to be specified. An error will be thrown if it is not, or
if the empty list was specified as argument to it.

[para]
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 prefix. The first argument is the number
of bytes which were transfered. The optional second argument is an
error message and added if and only if an error occured during the the
transfer.

[opt_def -progress [arg commandprefix]]

This option specifies the progress callback of the operation. It is
optional and defaults to the empty list. This last possibility signals
that no feedback was asked for and disabled it.

[para]

Its value has to be a command prefix, see above, [option -command] for
a more detailed explanation. When the callback is invoked a single
additional arguments is appended to the prefix. This argument is the
number of bytes which were transfered so far.

[opt_def -size [arg 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.

[para]

All transfer commands will throw error an when their user tries to
transfer more data than is available in the input. This happens
immediately, before the transfer is actually 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.

[opt_def -encoding    [arg encodingname]]
[opt_def -eofchar     [arg eofspec]]
[opt_def -translation [arg transspec]]

These options are the same as are recognized by the builtin command
[cmd 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 failure. None of
these options are required, and they default to the settings of the
output channel if not specified.

[list_end][comment options]
[list_end][comment definitions/api]

[vset CATEGORY transfer]
[include ../common-text/feedback.inc]
[manpage_end]
