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(elisp)Eval List

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Evaluation List Buffer
----------------------

   You can use the "evaluation list buffer", called `*edebug*', to
evaluate expressions interactively.  You can also set up the
"evaluation list" of expressions to be evaluated automatically each
time Edebug updates the display.

`E'
     Switch to the evaluation list buffer `*edebug*'
     (`edebug-visit-eval-list').

   In the `*edebug*' buffer you can use the commands of Lisp
Interaction mode (Note: Lisp Interaction.) as
well as these special commands:

`C-j'
     Evaluate the expression before point, in the outside context, and
     insert the value in the buffer (`edebug-eval-print-last-sexp').

`C-x C-e'
     Evaluate the expression before point, in the context outside of
     Edebug (`edebug-eval-last-sexp').

`C-c C-u'
     Build a new evaluation list from the contents of the buffer
     (`edebug-update-eval-list').

`C-c C-d'
     Delete the evaluation list group that point is in
     (`edebug-delete-eval-item').

`C-c C-w'
     Switch back to the source code buffer at the current stop point
     (`edebug-where').

   You can evaluate expressions in the evaluation list window with
`C-j' or `C-x C-e', just as you would in `*scratch*'; but they are
evaluated in the context outside of Edebug.

   The expressions you enter interactively (and their results) are lost
when you continue execution; but you can set up an "evaluation list"
consisting of expressions to be evaluated each time execution stops.

   To do this, write one or more "evaluation list groups" in the
evaluation list buffer.  An evaluation list group consists of one or
more Lisp expressions.  Groups are separated by comment lines.

   The command `C-c C-u' (`edebug-update-eval-list') rebuilds the
evaluation list, scanning the buffer and using the first expression of
each group.  (The idea is that the second expression of the group is the
value previously computed and displayed.)

   Each entry to Edebug redisplays the evaluation list by inserting each
expression in the buffer, followed by its current value.  It also
inserts comment lines so that each expression becomes its own group.
Thus, if you type `C-c C-u' again without changing the buffer text, the
evaluation list is effectively unchanged.

   If an error occurs during an evaluation from the evaluation list, the
error message is displayed in a string as if it were the result.
Therefore, expressions that use variables not currently valid do not
interrupt your debugging.

   Here is an example of what the evaluation list window looks like
after several expressions have been added to it:

     (current-buffer)
     #<buffer *scratch*>
     ;---------------------------------------------------------------
     (selected-window)
     #<window 16 on *scratch*>
     ;---------------------------------------------------------------
     (point)
     196
     ;---------------------------------------------------------------
     bad-var
     "Symbol's value as variable is void: bad-var"
     ;---------------------------------------------------------------
     (recursion-depth)
     0
     ;---------------------------------------------------------------
     this-command
     eval-last-sexp
     ;---------------------------------------------------------------

   To delete a group, move point into it and type `C-c C-d', or simply
delete the text for the group and update the evaluation list with `C-c
C-u'.  To add a new expression to the evaluation list, insert the
expression at a suitable place, insert a new comment line, then type
`C-c C-u'.  You need not insert dashes in the comment line--its
contents don't matter.

   After selecting `*edebug*', you can return to the source code buffer
with `C-c C-w'.  The `*edebug*' buffer is killed when you continue
execution, and recreated next time it is needed.