


transfer::data::sourcData transfer faciltransfer::data::source(n)


______________________________________________________________________________

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



transfer                       0.2                              1





transfer::data::sourcData transfer faciltransfer::data::source(n)


       following general form:

       objectName method ?arg arg ...?
              The  method method and its arg'uments determine the exact behav-
              ior 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 ini-
              tiated by the object is active is safe as all data required  for
              the transfer itself was copied, and the completion of the trans-
              fer 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  incom-
                     pletely. 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 con-
              taining 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 mes-
              sage describing the problem found with the configuration. Other-
              wise this variable is not touched.




transfer                       0.2                              2





transfer::data::sourcData transfer faciltransfer::data::source(n)


       objectName transmit channel blocksize done
              This  method  initiates a transfer of the referenced data to the
              specified channel.  When the transfer completes the command pre-
              fix  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  dif-
       ferent 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 immedi-
              ate 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  con-
              taining 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



transfer                       0.2                              3





transfer::data::sourcData transfer faciltransfer::data::source(n)


       of       the       Tcllib       SF       Trackers       [http://source-
       forge.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>













































transfer                       0.2                              4


