:trace top-level command

$Revision: 5.0.2.3 $

Arguments: &rest function-or-option-list

When called with no arguments, all the functions currently being traced are printed, otherwise the arguments to :trace are function names (symbols) or option lists. An option list starts with a function name, and the other elements of the list are options for tracing that particular function. The options for one function do not affect the tracing of any other function. The options come in pairs, the first element of the pair being the option name (i.e., a keyword), and the second part being the option value. Missing options default to nil. Here are some valid calls to :trace:

:trace foo

:trace foo (bar :break-before t) baz

:trace (baz :inside foo :break-before t)

:trace

Note that the following is invalid:

:trace foo :inside bar

You must enclose options in a list along with the function name and the option value. If you enter the invalid case above, Lisp will complain that :inside does not have a function definition.

The minimal abbreviation of :trace is :tr.

See top_level.htm for more information on top-level commands. See debugging.htm for information on the debugger and for examples of tracing.

The general documentation description is in introduction.htm. The index in index.htm.

valid options to :trace

Option	Arguments	Notes
:condition	expr	Trace this function if expr evaluates to a non-nil value.
:break-before	val	The expression val is evaluated just before entering a function, just after exiting a function, and at both times, respectively. If val evaluates to t, then a new break level is entered. Otherwise, execution continues. When used in combination with :inside, breaks only occur when the :inside condition is satisfied.
:break-after
:break-all
:inside	func	Trace this function if Lisp is currently inside the evaluation of the function func. func may also be a list of functions. For example, (trace (deeper :inside deep)) would trace the function deeper only when called from within a call to deep.
:print-before	expr	expr should either be a single object or a list of objects which will be evaluated. The results will be printed before entering or after leaving the function, or both, in the case of :print-all.
:print-after
:print-all