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option(3tk) Tk Built-In Commands option(3tk) 





NAME


option - Add/retrieve window options to/from the option
  database






SYNOPSIS


option add pattern value ?priority?
option clear
option get window name class
option readfile fileName ?priority?








DESCRIPTION


The option command allows you to add entries to the Tk
    option database or to retrieve options from the database. The add
    form of the command adds a new option to the database. Pattern
    contains the option being specified, and consists of names and/or classes
    separated by asterisks or dots, in the usual X format (see PATTERN
    FORMAT). Value contains a text string to associate with
    pattern; this is the value that will be returned in calls to
    Tk_GetOption or by invocations of the option get command. If
    priority is specified, it indicates the priority level for this
    option (see below for legal values); it defaults to interactive. This
    command always returns an empty string.


The option clear command clears the option database.
    Default options (from the RESOURCE_MANAGER property or the
    .Xdefaults file) will be reloaded automatically the next time an
    option is added to the database or removed from it. This command always
    returns an empty string.


The option get command returns the value of the option
    specified for window under name and class. If several
    entries in the option database match window, name, and
    class, then the command returns whichever was created with highest
    priority level. If there are several matching entries at the same
    priority level, then it returns whichever entry was most recently entered
    into the option database. If there are no matching entries, then the empty
    string is returned.


The readfile form of the command reads fileName,
    which should have the standard format for an X resource database such as
    .Xdefaults, and adds all the options specified in that file to the
    option database. If priority is specified, it indicates the priority
    level at which to enter the options; priority defaults to
    interactive.


The file is read through a channel which is in "utf-8"
    encoding, invalid byte sequences are automatically converted to valid ones.
    This means that encodings like ISO 8859-1 or cp1252 with high probability
    will work as well, but this cannot be guaranteed. This cannot be changed,
    setting the [encoding system] has no effect.


The priority arguments to the option command are
    normally specified symbolically using one of the following values:



  

  
Level 20. Used for default values hard-coded into widgets.

  

  
Level 40. Used for options specified in application-specific startup
      files.

  

  
Level 60. Used for options specified in user-specific defaults files, such
      as .Xdefaults, resource databases loaded into the X server, or
      user-specific startup files.

  

  
Level 80. Used for options specified interactively after the application
      starts running. If priority is not specified, it defaults to this
      level.




Any of the above keywords may be abbreviated. In addition,
    priorities may be specified numerically using integers between 0 and 100,
    inclusive. The numeric form is probably a bad idea except for new priority
    levels other than the ones given above.






PATTERN FORMAT


Patterns consist of a sequence of words separated by either
    periods, “.”, or asterisks “*”. The overall
    pattern may also be optionally preceded by an asterisk.


Each word in the pattern conventionally starts with either an
    upper-case letter (in which case it denotes the class of either a widget or
    an option) or any other character, when it denotes the name of a widget or
    option. The last word in the pattern always indicates the option; the
    preceding ones constrain which widgets that option will be looked for
  in.


When two words are separated by a period, the latter widget must
    be a direct child of the former (or the option must apply to only the
    indicated widgets). When two words are separated by an asterisk, any depth
    of widgets may lie between the former and latter widgets (and the option
    applies to all widgets that are children of the former widget).


If the overall pattern is preceded by an asterisk, then the
    overall pattern applies anywhere it can throughout the whole widget
    hierarchy. Otherwise the first word of the pattern is matched against the
    name and class of the “.” toplevel, which are
    usually set by options to wish.






EXAMPLES


Instruct every button in the application to have red text on it
    unless explicitly overridden, by setting the foreground for the
    Button class (note that on some platforms the option is ignored):




option add *Button.foreground red startupFile




Allow users to control what happens in an entry widget when the
    Return key is pressed by specifying a script in the option database and add
    a default option for that which rings the bell:




entry .e
bind .e <Return> [option get .e returnCommand Command]
option add *.e.returnCommand bell widgetDefault








SEE ALSO


options(3tk), wish(1)






KEYWORDS


database, option, priority, retrieve







  

    
    Tk