5.5 Tracing subfunctions

Subfunctions are functions that are defined inside the body of other functions rather than by top level definers like defun, defmethod, etc. To trace such a subfunction, call trace with a "subfunction dspec" in one of these forms:

• (subfunction sub-name parent-dspec)
• (flet sub-name parent-dspec)
• (labels sub-name parent-dspec)

See 7.6 Subfunction dspecs for details. All of the keywords that trace takes have the same effect for subfunction tracing.

The behavior when tracing a subfunction is somewhat different from tracing other function.

• trace modifies the parent of the subfunction such that future execution of the code that creates the subfunction will create it traced.
• A subsequent call to trace with the same dspec re-modifies the parent, and also causes any of the subfunctions that were already created traced to change their tracing behavior (as defined by the keywords to trace) to the behavior specified by the latest call to trace.
• untrace with the same dspec returns the parent function to its original state and switches off tracing for the subfunctions that were created traced.
• A call to trace with the same dspec after untrace modifies the parent as in the first point above, but has no effect on any subfunction that was created by the parent before the call to untrace.

Tracing of subfunction works only for compiled functions.

5.5.1 Notes on subfunction names

Anonymous lambdas are named by the compiler using integers.

You can find the dspec of a given subfunction by calling object-dspec on the subfunction. You can also construct it from the printed representation of the subfunction, which contains the sub-name and the parent-dspec.

A subfunction can be given an name using a hcl:lambda-name declaration (see declare). If this is of the form (subfunction sub-name), then the dspec of the subfunction will contain both sub-name and the correct parent-dspec. However, if it has any other form, then dspec will be that name and you will need to know the parent-dspec in order to construct the subfunction dspec.