tkoptiondb: Tk options database routines
In tclish: 'Tcl/Tk' Utilities Package

Description Usage Arguments Details Value Author(s) See Also Examples

These functions allow interaction with the Tk options resource database.

optiondb_add(pattern,
             value,
             priority="interactive",
             verbose=FALSE)
optiondb_get(widget=".",
             rsrcName,
             rsrcClass,
             verbose=FALSE)
optiondb_readfile(filename,
                  priority="userDefault",
                  verbose=FALSE)

`pattern`	character string containing the option being specified, and consists of names and/or classes separated by asterisks or dots, in the usual X format
`widget`	object of the class `tkwin` or character string specifying Tk widget from which to retrieve resource
`filename`	character string specifying pathname to resource file
`value`	character string specifying text to associate with pattern
`rsrcName`	character string specifying resource name
`rsrcClass`	character string specifying resource class name
`priority`	character string (or integer) specifying priority level for this option
`verbose`	logical scalar. If `TRUE`, displays the Tcl command

optiondb_add adds an entry into Tcl options database with given priority; optiondb_readfile adds a file's contents. To clear an entry, invoke optiondb_add with an empty string for value.

optiondb_get fetches a value from Tcl options database.

There is a fundamental difference between the way Tcl handles options and the way Xt handles options; Tcl has separate priorities and within a level prefers the latest matching option, Xt prefers options with "more exact" specifiers and has no level semantics.

A resource class name begins with a capital letter; the resource name begins with a lowercase letter.

There are four primary priority levels. From lowest to highest, they are:

widgetDefault: 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. (default)

In addition, priorities may be specified numerically using integers between 0 and 100, inclusive. However, the numeric form is discouraged.

The optiondb_get method returns a tclObj object representing the Tcl variable. Use the tclvalue method to extract its character string value.

The other methods are invoked for their side-effect.

P. Roebuck proebuck@mdanderson.org

tclvalue

  ## Not run: 
## Set a couple button resource values
optiondb_add("*Button.background", "red", "startupFile")
optiondb_add("*Button.width", 100, "startupFile")

## Even make up "fake" application-specific resources
optiondb_add("*foo", "bar", "userDefault")

## Prove it works
toplevel <- tktoplevel()
tkpack(button <- tkbutton(toplevel)) # large red button appears

## Fetch "fake" application-specific value
foo.obj <- optiondb_get(rsrcName="foo", rsrcClass="Foo")
foo <- as.character(tclvalue(foo.obj))  # bar

## Read an application-defaults file containing resources
optiondb_readfile("/path/to/app-defaults/myapp.ad")
  
## End(Not run)