Provided by: tcllib_1.14-dfsg-1_all bug

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 SF Trackers
       [http://sourceforge.net/tracker/?group_id=12883].   Please  also  report  any  ideas   for
       enhancements you may have for either package and/or documentation.

KEYWORDS

       channel, copy, data source, transfer

CATEGORY

       Transfer module

COPYRIGHT

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