Method: TkVariable#trace

Defined in:
lib/tk/variable.rb

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



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# File 'lib/tk/variable.rb', line 1375

def trace(opts, cmd = nil, &block)
  cmd ||= block
  opts = _check_trace_opt(opts)
  (@trace_var ||= []).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', 'variable',
                             @id, @trace_opts, 'rb_var ' << @id)
    else
      Tk.tk_call_without_enc('trace', 'add', '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