7.6 Subfunction dspecs

For some purposes, most usefully trace and defadvice, LispWorks allows dspecs that do not name a global definition, but a local function. These are of the form:

(subfunction sub-name parent-dspec)

where parent-dspec is another dspec (possibly a subfunction dspec itself). For flet and labels, it is also possible to use the form:

(flet sub-name parent-dspec)
	An alias for (subfunction (flet sub-name) parent-dspec).

or:

(labels sub-name parent-dspec)
	An alias for (subfunction (labels sub-name) parent-dspec).

sub-name is the name of the subfunction inside the parent, which by default is determined as follows:

• For subfunctions defined by flet and labels, the name is a two element list of the form (flet function-name) or (labels function-name), where function-name is the function name in the flet or labels definition.
• For anonymous lambdas, the compiler names the subfunctions within each parent function by small, increasing integers starting from 1.

You can override the default name by using the LispWorks-specific hcl:lambda-name declaration (see declare). Note that you should use the form:

(declare (lambda-name (subfunction sub-name))

to get a name that is useful for debugging. If you do not use subfunction, then the debugger cannot find the source for function.

Notes:

• The sub-name of the subfunction is not used by the dspec system to search its databases, so can be anything.
• Source level debugging does not use the sub-name of the subfunction, but does need to be able to find the definition of parent-dspec.
• trace and defadvice search for the function by comparing (using equal) the subfunction name in the dspec to the name of each subfunction in the parent function.
• A subfunction dspec can be canonicalized and prettified or passed as an argument to dspec-definition-locations (which will find where parent is defined).
• Additionally, pseudo-dspecs like this are allowed for top-level forms:

  (top-level-form (location tlf))
  

  location is an atomic location (not containing :inside, see 7.7.1 Locations) and tlf identifies the top-level form within that location. These are used as parent dspecs in subfunction dspecs and :inside locations. These dspecs can be canonicalized and prettified, and can be returned as dspecs from the location finders.