transfer::data::source -
Data source
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
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.
-
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.
All objects created by the
::transfer::data::source 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.
-
objectName 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 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 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.
-
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
containing 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
message describing the problem found with the configuration. Otherwise
this variable is not touched.
-
objectName 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.
All data sources support the options listed below. It should be noted
that the first four options are semi-exclusive, each specifying a
different 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 containing 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.
This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category
transfer of the
http://sourceforge.net/tracker/?group_id=12883.
Please also report any ideas for enhancements you may have for either
package and/or documentation.
transfer, copy, channel, data source