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 PATTERNFORMAT). 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 optionget 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 optionclear 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 optionget 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:
widgetDefault3
Level 20. Used for default values hard-coded into widgets.
startupFile
Level 40. Used for options specified in application-specific startup files.
userDefault
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.
interactive
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.