1transfer::data::source(n) Data transfer facilities transfer::data::source(n)
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8 transfer::data::source - Data source
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11 package require Tcl 8.4
12 package require snit ?1.0?
14 package require transfer::copy ?0.1?
16 package require transfer::data::source ?0.1?
18 transfer::data::source object ?options...?
20 object destroy
22 object type
24 object data
26 object size
28 object valid msgvar
30 object transmit channel blocksize done
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36 This package provides objects mainly describing the origin of some data
37 to transfer. They are also able to initiate transfers of the described
38 information to a channel using the foundation package transfer::copy.
39
41 transfer::data::source object ?options...?
42 This command creates and configures a new source object. The
43 fully qualified name of the object command is returned as the
44 result of the command.
45 The recognized options are listed below. It should be noted that
47 the first four options are semi-exclusive, each specifying a
48 different type of data source and associated content. If these
49 options are specified more than once then the last option speci‐
50 fied is used to actually configure the object.
51 -string text
53 This option specifies that the source of the data is an
54 immediate string, and its associated argument contains
55 the string in question.
56 -channel handle
58 This option specifies that the source of the data is a
59 channel, and its associated argument is the handle of the
60 channel containing the data.
61 -file path
63 This option specifies that the source of the data is a
64 file, and its associated argument is the path of the file
65 containing the data.
66 -variable varname
68 This option specifies that the source of the data is a
69 string stored in a variable, and its associated argument
70 contains the name of the variable in question. The vari‐
71 able is assumed to be global or namespaced, anchored at
72 the global namespace.
73 -size int
75 This option specifies the size of the data transfer. It
76 is optional and defaults to -1. This value, and any other
77 value less than zero signals to transfer all the data
78 from the source.
79 object destroy
81 This method destroys the object. Doing so while a transfer ini‐
82 tiated by the object is active is safe as all data required for
83 the transfer itself was copied, and the completion of the trans‐
84 fer will not try to access the initiating object anymore. i.e.
85 the transfer is completely separate from the source object
86 itself.
87 object type
89 This method returns a string describing the type of the data the
90 object is refering to. The possible values and their meanings
91 are:
92 undefined
94 No data was specified at all, or it was specified incom‐
95 pletely. The object does not know the type.
96 string The data to transfer is contained in a string.
98 channel
100 The data to transfer is contained in a channel.
101 object data
103 This method returns a value depending on the type of the data
104 the object refers to, through which the data can be accessed.
105 The method throws an error if the type is undefined. For type
106 string the returned result is the data itself, whereas for type
107 channel the returned result is the handle of the channel con‐
108 taining the data.
109 object size
111 This method returns a value depending on the type of the data
112 the object refers to, the size of the data. The method throws
113 an error if the type is undefined. Return of a negative value
114 signals that the object is unable to determine an absolute size
115 upfront (like for data in a channel).
116 object valid msgvar
118 This method checks the configuration of the object for validity.
119 It returns a boolean flag as result, whose value is True if the
120 object is valid, and False otherwise. In the latter case the
121 variable whose name is stored in msgvar is set to an error mes‐
122 sage describing the problem found with the configuration. Other‐
123 wise this variable is not touched.
124 object transmit channel blocksize done
126 This method initiates a transfer of the referenced data to the
127 specified channel. When the transfer completes the command pre‐
128 fix done is invoked, per the rules for the option -command of
129 command transfer::copy::do in the package transfer::copy. The
130 blocksize specifies the size of the chunks to transfer in one
131 go. See the option -blocksize of command transfer::copy::do in
132 the package transfer::copy.
133
135 channel, copy, data source, transfer
136
138 Copyright (c) 2006 Andreas Kupries <andreas_kupries@users.sourceforge.net>
139transfer 0.1 transfer::data::source(n)