7.6 Subfunction dspecs

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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/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) 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.

LispWorks User Guide and Reference Manual - 20 Sep 2017