NAME¶
transfer::data::source - Data source
SYNOPSIS¶
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
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¶
PACKAGE COMMANDS¶
- 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.
OBJECT 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.
OBJECT METHODS¶
- 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.
OPTIONS¶
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.
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 SF Trackers [
http://sourceforge.net/tracker/?group_id=12883].
Please also report any ideas for enhancements you may have for either package
and/or documentation.
KEYWORDS¶
channel, copy, data source, transfer
CATEGORY¶
Transfer module
COPYRIGHT¶
Copyright (c) 2006-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>