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Editorial Team
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Asked: 2026-05-23T19:31:41+00:00

I am trying to abstract my menu buttons and functions associated with it to

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I am trying to abstract my menu buttons and functions associated with it to a single proc call (addMenus function below). The following code builds the menu buttons correctly but on pressing the buttons (say Open) it errors out as:

Error: invalid command name “myputs Open”

  • I think I am not using the quotes properly. Any pointers on fixing this?
  • Also any suggestions on improving the code especially if I want to pass arguments to menubutton or menu command?
proc myputs { label } {
  puts $label
}

proc addMenus { mbar myargs } {
  foreach { arg } $myargs {
    foreach { button options } $arg {
      set x ${mbar}.[string tolower ${button}] 
      set y ${x}.menu

      menubutton $x -text $button -menu $y
      pack $x -side left
      set mdropoff [menu $y -tearoff 0]

      foreach { label command } $options {
        $mdropoff add command -label $label -command $command
      }
    }
  }
}

#----------------------------------------
# main script
#----------------------------------------
wm title . "My Gui"

# build the frame which contains menu options
set mbar .mbar
frame $mbar -relief raised -bd 2
pack  $mbar -side top -fill x 

# text box as a filler
text .myout -width 40 -height 20
pack .myout -side top -fill both -expand true

# file menu
set myargs {
  { 
    File {
    "Open ..."     { [list myputs "Open"] }
    "New  ..."     { [list myputs "New"] }
    "Save ..."     { [list myputs "Save"] }
    "Save As ..."  { [list myputs "Save As"] }
    } 
  }
  { 
    Edit {
    "Cut"          { [list myputs "Cut"] }
    "Copy"         { [list myputs "Copy"] }
    "Paste"        { [list myputs "Paste"] }
    } 
  }
}

addMenus $mbar $myargs
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1 Answer

  1. Editorial Team

    The issue is exactly that Tcl doesn’t do any expansion of scripts nested inside data structures like that (it can’t; it doesn’t know what they are until you tell it). There are a few possibilities for dealing with it:

    1. Write your code to not need it (using plain myputs "Open" instead of [list myputs "Open"] in your data).

    2. Construct your data with list throughout:

      set myargs [list [list "File" \
    [list "Open ..." [list myputs "Open"]] \
    [list "New ..." [list myputs "New"]] \
    [list "Save ..." [list myputs "Save"]] \
    [list "Save As ..." [list myputs "Save As"]] \
] [list "Edit" \
    ...

      OK, it’s going to give you backslashitis (or very long lines).

    3. Use a bit of trickery with uplevel and subst. From inside addMenus…

      foreach { label command } $options {
  set command [uplevel 1 [list subst $command]]
  $mdropoff add command -label $label -command $command
}

      That’ll make your code otherwise look like what you expect (and expand any embedded variables in the calling context, which is usually what you want; if you never use variables in the menu description – or complex namespace handling – you can use a simpler set command [subst $command]). But it is significantly trickier than anything you had before as you’re moving from simple calls to something more template-based.

    And if you’re wanting some substitutions to happen at one time and others at another, it’s time to use helper procedures: your brain (and anyone maintaining the code) will thank you.

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