:local

Arguments: [:i] [:c] [:x] [:r] [name|index]

If not in ldb mode (ldb does not appear in the prompt), this command prints information on local variables in the current frame, as we now describe. See below for behavior in ldb mode.

This command causes the values of local variables for the current stack frame (see :zoom) to be printed. See debugging.htm for information on the handling of local variables by the debugger.

Note that the compiler may not save the names of local variables in compiled code. In that case variables will be listed identified by an index, which is a number from 0 to n-1, where n is the number of compiled local variables. The compiler will save names of compiled local variables if the compiler switch compiler:save-local-names-switch is bound to a function which returns t. Further, local name information is only loaded from compiled file is the variable *load-local-names-info* is non-nil when the compiled (fasl) file is loaded. (There is an example on the *load-local-names-info* page showing :local output when local names are and are not loaded.)

When local names are saved (as described in the paragraph above), closure variables are also printed out.

If the name/index option is specified, the value of the local variable identified by the name or index will be printed. With no other options, all instances of name are looked for. If the option :i (:c) is specified, just interpreted (compiled) code is searched for name. index always refers to compiled local variables. The variable cl:* is set only if you specify a name or index argument to :local. The commands :local, :local :i and :local :c do not set *.

The :x argument, if specified, causes any numeric values to be printed in hexadecimal. (The related :set-local does not support the :x argument.)

The :r option

The :r argument, if specified, displays locals in raw layout. That means they are not interpreted as required, optional, local, etc., just all as raw-local.

If :r is specified, the name/index argument should be index. Names in raw mode are always :unknown. The purpose of this option is to access the stack in a way similar to the way the garbage collector and heap-walkers access it. Both the gc and heapwalkers use the same stack frame walker to look at various slots in the stack. This includes all argument and local slots, but it also includes slots not normally visible by the debugger; for example, slots within a stack-allocated object are not normally shown normally, but are shown with the :r option.

When :r is specified, the result differs from when it is not in the following ways:

• The ordering tends to be opposite: ascending locals under normal display appear as descending under the :r option.
• The arguments to the function are not interpreted in :r mode. Usually the :r mode shows locations in the stack which constitute the next newer frame's arguments, so one would have to move to the next older frame before being able to see the arguments seen under normal mode. No atempt to reconstruct a calling expression for this frame is made, so some arguments which reside as not-given keywords are not interpreted as such. If &rest arguments are rearranged, no attempt to expand them are made.
• If there are stack-allocated objects, the header words in each will appear as non-lisp-objects, and likely any filler words or empty space in the objects will also be either non-lisp objects, or else objects that have survived from previous function invocations. Sometimes stack space is allocated for stack-objects, but the objects or parts of the objects are not initialized during a particular function invocation, so the previous objets refernced from the stack are still seen. It is these references that are potential memory leaks.

Further notes

The minimal abbreviation for :local is :loc.

See also :set-local.

This command operates on the focused process when multiprocessing is active. See :focus.

:local in ldb mode

When in ldb-step mode, the :local command works as follows:

When a breakpoint is hit, the default current frame is the context in which the breakpoint occurred (and thus ldb-step mode was entered). If at this frame, the :local command is given with no arguments, a list of all registers is printed, along with their values. The names of the registers can be used in the :local command to print only one value, just as in a regular frame.

The :x modifier can be used to ask for any numeric output in hexadecimal. Typical register names start with :% and are named according to hardware convention, eg. :%r10, :%ebx (on x86), :%i3 (on sparc).

See top-level.htm for more information on top-level commands. See debugging.htm for information on the debugger.

Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
The object described on this page has been modified in the 9.0 release; see the Release Notes.
Created 2019.8.20.