Ubuntu Manpage: transfer::data::source

NAME

       transfer::data::source - Data source

SYNOPSIS

       package require Tcl  8.4

       package require snit  ?1.0?

       package require transfer::copy  ?0.2?

       package require transfer::data::source  ?0.2?

       transfer::data::source objectName ?options...?

       objectName method ?arg arg ...?

       objectName destroy

       objectName type

       objectName data

       objectName size

       objectName valid msgvar

       objectName transmit channel blocksize done

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DESCRIPTION

       This  package provides objects mainly describing the origin of some data to transfer. They
       are also able to initiate transfers of the described information to a  channel  using  the
       foundation package transfer::copy.

API

PACKAGE COMMANDS
transfer::data::source objectName ?options...?
This command creates a new data source object with an associated Tcl command whose
name is objectName. This object command is explained in full detail in the
sections Object command and Object methods. The set of supported options is
explained in section Options.

The object command will be created under the current namespace if the objectName is
not fully qualified, and in the specified namespace otherwise. The fully qualified
name of the object command is returned as the result of the command.

OBJECT COMMAND
All objects created by the ::transfer::data::source command have the following general
form:

objectName method ?arg arg ...?
The method method and its arg'uments determine the exact behavior of the command.
See section Object methods for the detailed specifications.

OBJECT METHODS
objectName destroy
This method destroys the object. Doing so while a transfer initiated by the object
is active is safe as all data required for the transfer itself was copied, and the
completion of the transfer will not try to access the initiating object anymore.
i.e. the transfer is completely separate from the source object itself.

objectName type
This method returns a string describing the type of the data the object is refering
to. The possible values and their meanings are:

undefined
No data was specified at all, or it was specified incompletely. The object
does not know the type.

string The data to transfer is contained in a string.

channel
The data to transfer is contained in a channel.

objectName data
This method returns a value depending on the type of the data the object refers to,
through which the data can be accessed. The method throws an error if the type is
undefined. For type string the returned result is the data itself, whereas for type
channel the returned result is the handle of the channel containing the data.

objectName size
This method returns a value depending on the type of the data the object refers to,
the size of the data. The method throws an error if the type is undefined. Return
of a negative value signals that the object is unable to determine an absolute size
upfront (like for data in a channel).

objectName valid msgvar
This method checks the configuration of the object for validity. It returns a
boolean flag as result, whose value is True if the object is valid, and False
otherwise. In the latter case the variable whose name is stored in msgvar is set to
an error message describing the problem found with the configuration. Otherwise
this variable is not touched.

objectName transmit channel blocksize done
This method initiates a transfer of the referenced data to the specified channel.
When the transfer completes the command prefix done is invoked, per the rules for
the option -command of command transfer::copy::do in the package transfer::copy.
The blocksize specifies the size of the chunks to transfer in one go. See the
option -blocksize of command transfer::copy::do in the package transfer::copy.

OPTIONS
All data sources support the options listed below. It should be noted that the first four
options are semi-exclusive, each specifying a different type of data source and associated
content. If these options are specified more than once then the last option specified is
used to actually configure the object.

-string text
This option specifies that the source of the data is an immediate string, and its
associated argument contains the string in question.

-channel handle
This option specifies that the source of the data is a channel, and its associated
argument is the handle of the channel containing the data.

-file path
This option specifies that the source of the data is a file, and its associated
argument is the path of the file containing the data.

-variable varname
This option specifies that the source of the data is a string stored in a variable,
and its associated argument contains the name of the variable in question. The
variable is assumed to be global or namespaced, anchored at the global namespace.

-size int
This option specifies the size of the data transfer. It is optional and defaults to
-1. This value, and any other value less than zero signals to transfer all the data
from the source.

-progress command
This option, if specified, defines a command to be invoked for each chunk of bytes
transmitted, allowing the user to monitor the progress of the transmission of the
data. The callback is always invoked with one additional argument, the number of
bytes transmitted so far.

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.

KEYWORDS

       channel, copy, data source, transfer

COPYRIGHT

       Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>