transfer::data::source(n) Data transfer facilities transfer::data::source(n)
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NAME
transfer::data::source - Data source
SYNOPSIS
package require Tcl 8.4
package require snit ?1.0?
package require transfer::copy ?0.1?
package require transfer::data::source ?0.1?
transfer::data::source object ?options...?
object destroy
object type
object data
object size
object valid msgvar
object transmit channel blocksize done
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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
transfer::data::source object ?options...?
This command creates and configures a new source object. The fully qualified name of the object command is returned as the result of
the command.
The recognized options are 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 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 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.
object 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 trans-
fer is completely separate from the source object itself.
object 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.
object 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.
object 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).
object 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.
object 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.
KEYWORDS
channel, copy, data source, transfer
COPYRIGHT
Copyright (c) 2006 Andreas Kupries <andreas_kupries@users.sourceforge.net>
transfer 0.1 transfer::data::source(n)