Tcl Bundled Packages dde(1T)
NAME
dde - Execute a Dynamic Data Exchange command
SYNOPSIS
package require dde 1.2
dde eval ?-async? service cmd ?arg ...?
dde execute ?-async? service topic data
dde poke service topic item data
dde request ?-binary? service topic data
dde servername ?topic?
dde services service topic
DESCRIPTION
This command allows an application to send Dynamic Data
Exchange (DE) command when running under Microsoft Windows.
Dynamic Data Exchange is a mechanism where applications can
exchange raw data. Each DE transaction needs a service name
and a topic. Both the service name and topic are application
defined; Tcl uses the service name TclEval, while the topic
name is the name of the interpreter given by dde servername.
Other applications have their own service names and topics.
For instance, Microsoft Excel has the service name Excel.
The eval and execute commands accept the option -async:
DE COMANDS
The following commands are a subset of the full Dynamic Data
Exchange set of commands.
dde servername ?topic?
dde servername registers the interpreter as a DE
server with the service name TclEval and the topic name
specified by topic. If no topic is given, dde server-
name returns the name of the current topic or the empty
string if it is not registered as a service.
dde execute ?-async? service topic data
dde execute takes the data and sends it to the server
indicated by service with the topic indicated by topic.
Typically, service is the name of an application, and
topic is a file to work on. The data field is given to
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Tcl Bundled Packages dde(1T)
the remote application. Typically, the application
treats the data field as a script, and the script is
run in the application. The -async option requests
asynchronous invocation. The command returns an error
message if the script did not run, unless the -async
flag was used, in which case the command returns
immediately with no error.
dde poke service topic item data
dde poke passes the data to the server indicated by
service using the topic and item specified. Typically,
service is the name of an application. topic is appli-
cation specific but can be a command to the server or
the name of a file to work on. The item is also appli-
cation specific and is often not used, but it must
always be non-null. The data field is given to the
remote application.
dde request ?-binary? service topic item
dde request is typically used to get the value of some-
thing; the value of a cell in Microsoft Excel or the
text of a selection in Microsoft Word. service is typi-
cally the name of an application, topic is typically
the name of the file, and item is application-specific.
The command returns the value of item as defined in the
application. Normally this is interpreted to be a
string with terminating null. If -binary is specified,
the result is returned as a byte array.
dde services service topic
dde services returns a list of service-topic pairs that
currently exist on the machine. If service and topic
are both null strings ({}), then all service-topic
pairs currently available on the system are returned.
If service is null and topic is not, then all services
with the specified topic are returned. If service is
not null and topic is, all topics for a given service
are returned. If both are not null, if that service-
topic pair currently exists, it is returned; otherwise,
null is returned.
dde eval ?-async? topic cmd ?arg arg ...?
dde eval evaluates a command and its arguments using
the interpreter specified by topic. The DE service
must be the TclEval service. The -async option
requests asynchronous invocation. The command returns
an error message if the script did not run, unless the
-async flag was used, in which case the command returns
immediately with no error. This command can be used to
replace send on Windows.
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Tcl Bundled Packages dde(1T)
DE AND TCL
A Tcl interpreter always has a service name of TclEval.
Each different interpreter of all running Tcl applications
must be given a unique name specified by dde servername.
Each interp is available as a DE topic only if the dde ser-
vername command was used to set the name of the topic for
each interp. So a dde services TclEval {} command will
return a list of service-topic pairs, where each of the
currently running interps will be a topic.
When Tcl processes a dde execute command, the data for the
execute is run as a script in the interp named by the topic
of the dde execute command.
When Tcl processes a dde request command, it returns the
value of the variable given in the dde command in the con-
text of the interp named by the dde topic. Tcl reserves the
variable $TCLEVAL$EXECUTE$RESULT for internal use, and dde
request commands for that variable will give unpredictable
results.
An external application which wishes to run a script in Tcl
should have that script store its result in a variable, run
the dde execute command, and the run dde request to get the
value of the variable.
When using DE, be careful to ensure that the event queue is
flushed using either update or vwait. This happens by
default when using wish unless a blocking command is called
(such as exec without adding the & to place the process in
the background). If for any reason the event queue is not
flushed, DE commands may hang until the event queue is
flushed. This can create a deadlock situation.
EXAMPLE
This asks Internet Explorer (which must already be running)
to go to a particularly important website:
package require dde
dde execute iexplore WOpenURL http:/www.tcl.tk/
SEE ALSO
tk(1T), winfo(1T), send(1T)
KEYWORDS
application, dde, name, remote execution
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
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Tcl Bundled Packages dde(1T)
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWTcl
Interface Stability Uncommitted
NOTES
Source for Tcl is available on http:/opensolaris.org.
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