Go to main content

man pages section 1: User Commands

Exit Print View

Updated: Thursday, June 13, 2019
 
 

dde (1t)

Name

dde - Execute a Dynamic Data Exchange command

Synopsis

package require dde 1.4

dde servername ?-force? ?-handler proc? ?--? ?topic?

dde execute ?-async? ?-binary? service topic data                       |

dde poke ?-binary? service topic item data

dde request ?-binary? service topic item

dde services service topic

dde eval ?-async? topic cmd ?arg arg ...?

Description

dde(1t)                      Tcl Bundled Packages                      dde(1t)



______________________________________________________________________________

NAME
       dde - Execute a Dynamic Data Exchange command

SYNOPSIS
       package require dde 1.4

       dde servername ?-force? ?-handler proc? ?--? ?topic?

       dde execute ?-async? ?-binary? service topic data                       |

       dde poke ?-binary? service topic item data

       dde request ?-binary? service topic item

       dde services service topic

       dde eval ?-async? topic cmd ?arg arg ...?
______________________________________________________________________________


DESCRIPTION
       This  command allows an application to send Dynamic Data Exchange (DDE)
       command when running under Microsoft Windows. Dynamic Data Exchange  is
       a mechanism where applications can exchange raw data. Each DDE transac-
       tion 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.

DDE COMMANDS
       The following commands are a subset of the full Dynamic  Data  Exchange
       set of commands.

       dde servername ?-force? ?-handler proc? ?--? ?topic?
              dde  servername  registers  the interpreter as a DDE server with
              the service name TclEval and the topic name specified by  topic.
              If  no  topic  is  given, dde servername returns the name of the
              current topic or the empty string if it is not registered  as  a
              service.  If the given topic name is already in use, then a suf-
              fix of the form " #2" or " #3" is appended to the name  to  make
              it  unique. The command's result will be the name actually used.
              The -force option is used to force registration of precisely the
              given topic name.

              The  -handler  option  specifies  a  Tcl  procedure that will be
              called to process calls to the dde server. If  the  package  has
              been  loaded  into  a safe interpreter then a -handler procedure
              must be defined. The procedure is called with all the  arguments
              provided by the remote call.

       dde execute ?-async? ?-binary? 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 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.  With- |
              out the -binary option all data will be sent in unicode. For dde |
              clients  which  don't implement the CF_UNICODE clipboard format, |
              this will automatically be translated to  the  system  encoding. |
              You can use the -binary option in combination with the result of |
              encoding convertto to send data in any other encoding.

       dde poke ?-binary? 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 application specific  but  can
              be  a  command  to  the server or the name of a file to work on.
              The item is also application specific and is often not used, but
              it  must  always  be  non-null.   The data field is given to the
              remote application.  Without the -binary option all data will be |
              sent  in  unicode.  For  dde  clients  which don't implement the |
              CF_UNICODE clipboard format, this will automatically  be  trans- |
              lated  to the system encoding. You can use the -binary option in |
              combination with the result of encoding convertto to  send  data |
              in any other encoding.

       dde request ?-binary? service topic item
              dde request is typically used to get the value of something; the
              value of a cell in Microsoft Excel or the text of a selection in
              Microsoft Word. service is typically the name of an application,
              topic is typically the name of the file, and  item  is  applica-
              tion-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  cur-
              rently exist on the machine. If service and topic are both empty
              strings ({}), then all service-topic pairs  currently  available
              on  the  system  are  returned. If service is empty and topic is
              not, then all services with the specified topic are returned. If
              service  is  non-empty and topic is, all topics for a given ser-
              vice are returned. If both are non-empty, if that  service-topic
              pair  currently  exists,  it  is  returned;  otherwise, an empty
              string is returned.

       dde eval ?-async? topic cmd ?arg arg ...?
              dde eval evaluates a command and its arguments using the  inter-
              preter  specified  by topic. The DDE 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.

DDE 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  DDE  topic
       only  if  the  dde  servername  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 context 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 com-
       mand, and then run dde request to get the value of the variable.

       When using DDE, 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, DDE 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 -async iexplore WWW_OpenURL http://www.tcl.tk/


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | runtime/tcl-8    |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       tk(n), winfo(n), send(n)

KEYWORDS
       application, dde, name, remote execution



NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source was downloaded from  http://prdownloads.sourceforge.net/tcl/tcl-
       core8.6.7-src.tar.gz

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.



dde                                   1.4                              dde(1t)