1transfer::data::source(n)  Data transfer facilities  transfer::data::source(n)
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5______________________________________________________________________________
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NAME

8       transfer::data::source - Data source
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SYNOPSIS

11       package require Tcl  8.4
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13       package require snit  ?1.0?
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15       package require transfer::copy  ?0.2?
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17       package require transfer::data::source  ?0.2?
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19       transfer::data::source objectName ?options...?
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21       objectName method ?arg arg ...?
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23       objectName destroy
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25       objectName type
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27       objectName data
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29       objectName size
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31       objectName valid msgvar
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33       objectName transmit channel blocksize done
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35______________________________________________________________________________
36

DESCRIPTION

38       This package provides objects mainly describing the origin of some data
39       to transfer. They are also able to initiate transfers of the  described
40       information to a channel using the foundation package transfer::copy.
41

API

43   PACKAGE COMMANDS
44       transfer::data::source objectName ?options...?
45              This command creates a new data source object with an associated
46              Tcl command whose name is objectName.  This  object  command  is
47              explained  in full detail in the sections Object command and Ob‐
48              ject methods. The set of supported options is explained in  sec‐
49              tion Options.
50
51              The  object  command will be created under the current namespace
52              if the objectName is not fully qualified, and in  the  specified
53              namespace  otherwise.   The  fully  qualified name of the object
54              command is returned as the result of the command.
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56   OBJECT COMMAND
57       All objects created by the ::transfer::data::source  command  have  the
58       following general form:
59
60       objectName method ?arg arg ...?
61              The  method method and its arg'uments determine the exact behav‐
62              ior of the command.  See section Object methods for the detailed
63              specifications.
64
65   OBJECT METHODS
66       objectName destroy
67              This  method destroys the object. Doing so while a transfer ini‐
68              tiated by the object is active is safe as all data required  for
69              the transfer itself was copied, and the completion of the trans‐
70              fer will not try to access the initiating object  anymore.  i.e.
71              the  transfer  is completely separate from the source object it‐
72              self.
73
74       objectName type
75              This method returns a string describing the type of the data the
76              object  is  refering  to. The possible values and their meanings
77              are:
78
79              undefined
80                     No data was specified at all, or it was specified  incom‐
81                     pletely. The object does not know the type.
82
83              string The data to transfer is contained in a string.
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85              channel
86                     The data to transfer is contained in a channel.
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88       objectName data
89              This  method  returns  a value depending on the type of the data
90              the object refers to, through which the data  can  be  accessed.
91              The  method  throws  an error if the type is undefined. For type
92              string the returned result is the data itself, whereas for  type
93              channel  the  returned  result is the handle of the channel con‐
94              taining the data.
95
96       objectName size
97              This method returns a value depending on the type  of  the  data
98              the  object  refers to, the size of the data.  The method throws
99              an error if the type is undefined. Return of  a  negative  value
100              signals  that the object is unable to determine an absolute size
101              upfront (like for data in a channel).
102
103       objectName valid msgvar
104              This method checks the configuration of the object for validity.
105              It  returns a boolean flag as result, whose value is True if the
106              object is valid, and False otherwise. In  the  latter  case  the
107              variable  whose name is stored in msgvar is set to an error mes‐
108              sage describing the problem found with the configuration. Other‐
109              wise this variable is not touched.
110
111       objectName transmit channel blocksize done
112              This  method  initiates a transfer of the referenced data to the
113              specified channel.  When the transfer completes the command pre‐
114              fix  done  is  invoked, per the rules for the option -command of
115              command transfer::copy::do in the package  transfer::copy.   The
116              blocksize  specifies  the  size of the chunks to transfer in one
117              go. See the option -blocksize of command  transfer::copy::do  in
118              the package transfer::copy.
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120   OPTIONS
121       All  data  sources support the options listed below. It should be noted
122       that the first four options are semi-exclusive, each specifying a  dif‐
123       ferent type of data source and associated content. If these options are
124       specified more than once then the last option specified is used to  ac‐
125       tually configure the object.
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127       -string text
128              This  option specifies that the source of the data is an immedi‐
129              ate string, and its associated argument contains the  string  in
130              question.
131
132       -channel handle
133              This  option specifies that the source of the data is a channel,
134              and its associated argument is the handle of  the  channel  con‐
135              taining the data.
136
137       -file path
138              This option specifies that the source of the data is a file, and
139              its associated argument is the path of the file  containing  the
140              data.
141
142       -variable varname
143              This  option  specifies  that the source of the data is a string
144              stored in a variable, and its associated argument  contains  the
145              name  of the variable in question. The variable is assumed to be
146              global or namespaced, anchored at the global namespace.
147
148       -size int
149              This option specifies the size of the data transfer. It  is  op‐
150              tional  and defaults to -1. This value, and any other value less
151              than zero signals to transfer all the data from the source.
152
153       -progress command
154              This option, if specified, defines a command to be  invoked  for
155              each  chunk  of  bytes transmitted, allowing the user to monitor
156              the progress of the transmission of the data.  The  callback  is
157              always invoked with one additional argument, the number of bytes
158              transmitted so far.
159

BUGS, IDEAS, FEEDBACK

161       This document, and the package it describes, will  undoubtedly  contain
162       bugs  and  other problems.  Please report such in the category transfer
163       of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist].   Please
164       also  report any ideas for enhancements you may have for either package
165       and/or documentation.
166
167       When proposing code changes, please provide unified diffs, i.e the out‐
168       put of diff -u.
169
170       Note  further  that  attachments  are  strongly  preferred over inlined
171       patches. Attachments can be made by going  to  the  Edit  form  of  the
172       ticket  immediately  after  its  creation, and then using the left-most
173       button in the secondary navigation bar.
174

KEYWORDS

176       channel, copy, data source, transfer
177

CATEGORY

179       Transfer module
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182       Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>
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187tcllib                                0.2            transfer::data::source(n)
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