bionic (3) ddest.3tcl.gz

NAME

       transfer::data::destination - Data destination

SYNOPSIS

       package require Tcl  8.4

       package require snit  ?1.0?

       package require transfer::data::destination  ?0.2?

       transfer::data::destination objectName ?options...?

       objectName method ?arg arg ...?

       objectName destroy

       objectName put chunk

       objectName done

       objectName valid msgvar

       objectName receive channel done

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DESCRIPTION

       This package provides objects mainly describing the destination of a data transfer. They are also able to
       initiate the reception of information from a channel into the described destination.

API

       transfer::data::destination objectName ?options...?
              This command creates a new data destination 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::destination 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  the  object  is busy with the reception of
              information from a channel will cause errors later on, when the reception completes and  tries  to
              access the now missing data structures of the destroyed object.

       objectName put chunk
              The main receptor method. Saves the received chunk of data into the configured destination. It has
              to be called for each piece of data received.

       objectName done
              The secondary receptor method. Finalizes the receiver. It has to  be  called  when  the  receiving
              channel signals EOF. Afterward neither itself nor method put can be called anymore.

       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 receive channel done
              This method initiates the reception of data from the specified channel. The received data will  be
              stored into the configured destination, via calls to the methods put and done.  When the reception
              completes the command prefix done is invoked, with the number of received characters  appended  to
              it as the sole additional argument.

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

       -channel handle
              This  option  specifies that the destination of the data is a channel, and its associated argument
              is the handle of the channel to write the received data to.

       -file path
              This option specifies that the destination of the data is a file, and its associated  argument  is
              the path of the file to write the received data to.

       -variable varname
              This  option specifies that the destination of the data is a variable, and its associated argument
              contains the name of the variable to write the received data to. The variable  is  assumed  to  be
              global or namespaced, anchored at the global namespace.

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

CATEGORY

       Transfer module

COPYRIGHT

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