Method: TkVariable#trace_element

Defined in:
lib/tk/variable.rb

#trace_element(elem, opts, cmd = nil, &block) ⇒ Object 



1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
 
# File 'lib/tk/variable.rb', line 1416

def trace_element(elem, opts, cmd = nil, &block)
  cmd ||= block
  if @elem
    fail(RuntimeError,
         "invalid for a TkVariable which denotes an element of Tcl's array")
  end

  opts = _check_trace_opt(opts)

  ((@trace_elem ||= {})[elem] ||= []).unshift([opts,cmd])

  if @trace_opts == nil
    TkVar_CB_TBL[@id] = self
    @trace_opts = opts.dup
    if USE_OLD_TRACE_OPTION_STYLE
      Tk.tk_call_without_enc('trace', 'add', 'variable',
                             @id, @trace_opts, 'rb_var ' << @id)
    else
      Tk.tk_call_without_enc('trace', 'variable',
                             @id, @trace_opts, 'rb_var ' << @id)
    end
  else
    newopts = @trace_opts.dup
    if USE_OLD_TRACE_OPTION_STYLE
      opts.each_byte{|c| newopts.concat(c.chr) unless newopts.index(c.chr)}
      if newopts != @trace_opts
        Tk.tk_call_without_enc('trace', 'vdelete',
                               @id, @trace_opts, 'rb_var ' << @id)
        @trace_opts.replace(newopts)
        Tk.tk_call_without_enc('trace', 'variable',
                               @id, @trace_opts, 'rb_var ' << @id)
      end
    else
      newopts |= opts
      unless (newopts - @trace_opts).empty?
        Tk.tk_call_without_enc('trace', 'remove', 'variable',
                               @id, @trace_opts, 'rb_var ' << @id)
        @trace_opts.replace(newopts)
        Tk.tk_call_without_enc('trace', 'add', 'variable',
                               @id, @trace_opts, 'rb_var ' << @id)
      end
    end
  end

  self
end