Provided by: tcllib_1.19-dfsg-2_all 
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
________________________________________________________________________________________________________________
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.
When proposing code changes, please provide unified diffs, i.e the output 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, data source, transfer
CATEGORY
Transfer module
COPYRIGHT
Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>