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 Trackers [
http://core.tcl.tk/tcllib/reportlist]. 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>