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Add GDS test and documentation files

Browse source 
(Transferred from the remains of the old standalone guile-debugging
project at gna.org.)

* emacs/gds-faq.txt, emacs/gds-test.el, emacs/gds-test.sh,
  emacs/gds-test.stdin, emacs/gds-tutorial.txt: New files.
This commit is contained in:
Neil Jerram 2008-12-12 22:32:59 +00:00
parent 8b08722023
commit 1a2285752e
5 changed files with 617 additions and 0 deletions
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225
emacs/gds-faq.txt Executable file
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* Installation
** How do I install guile-debugging?
After unpacking the .tar.gz file, run the usual sequence of commands:
$ ./configure
$ make
$ sudo make install
Then you need to make sure that the directory where guile-debugging's
Scheme files were installed is included in your Guile's load path.
(The sequence above will usually install guile-debugging under
/usr/local, and /usr/local is not in Guile's load path by default,
unless Guile itself was installed under /usr/local.) You can discover
your Guile's default load path by typing
$ guile -q -c '(begin (write %load-path) (newline))'
There are two ways to add guile-debugging's installation directory to
Guile's load path, if it isn't already there.
1. Edit or create the `init.scm' file, which Guile reads on startup,
so that it includes a line like this:
(set! %load-path (cons "/usr/local/share/guile" %load-path))
but with "/usr/local" replaced by the prefix that you installed
guile-debugging under, if not /usr/local.
The init.scm file must be installed (if it does not already exist
there) in one of the directories in Guile's default load-path.
2. Add this line to your .emacs file:
(setq gds-scheme-directory "/usr/local/share/guile")
before the `require' or `load' line that loads GDS, but with
"/usr/local" replaced by the prefix that you installed
guile-debugging under, if not /usr/local.
Finally, if you want guile-debugging's GDS interface to be loaded
automatically whenever you run Emacs, add this line to your .emacs:
(require 'gds)
* Troubleshooting
** "error in process filter" when starting Emacs (or loading GDS)
This is caused by an internal error in GDS's Scheme code, for which a
backtrace will have appeared in the gds-debug buffer, so please switch
to the gds-debug buffer and see what it says there.
The most common cause is a load path problem: Guile cannot find GDS's
Scheme code because it is not in the known load path. In this case
you should see the error message "no code for module" somewhere in the
backtrace. If you see this, please try the remedies described in `How
do I install guile-debugging?' above, then restart Emacs and see if
the problem has been cured.
If you don't see "no code for module", or if the described remedies
don't fix the problem, please send the contents of the gds-debug
buffer to me at <neil@ossau.uklinux.net>, so I can debug the problem.
If you don't see a backtrace at all in the gds-debug buffer, try the
next item ...
** "error in process filter" at some other time
This is caused by an internal error somewhere in GDS's Emacs Lisp
code. If possible, please
- switch on the `debug-on-error' option (M-x set-variable RET
debug-on-error RET t RET)
- do whatever you were doing so that the same error happens again
- send the Emacs Lisp stack trace which pops up to me at
<neil@ossau.uklinux.net>.
If that doesn't work, please just mail me with as much detail as
possible of what you were doing when the error occurred.
* GDS Features
** How do I inspect variable values?
Type `e' followed by the name of the variable, then <RET>. This
works whenever GDS is displaying a stack for an error at at a
breakpoint. (You can actually `e' to evaluate any expression in the
local environment of the selected stack frame; inspecting variables is
the special case of this where the expression is only a variable name.)
If GDS is displaying the associated source code in the window above or
below the stack, you can see the values of any variables in the
highlighted code just by hovering your mouse over them.
** How do I change a variable's value?
Type `e' and then `(set! VARNAME NEWVAL)', where VARNAME is the name
of the variable you want to set and NEWVAL is an expression which
Guile can evaluate to get the new value. This works whenever GDS is
displaying a stack for an error at at a breakpoint. The setting will
take effect in the local environment of the selected stack frame.
** How do I change the expression that Guile is about to evaluate?
Type `t' followed by the expression that you want Guile to evaluate
instead, then <RET>.
Then type one of the commands that tells Guile to continue execution.
(Tweaking expressions, as described here, is only supported by the
latest CVS version of Guile. The GDS stack display tells you when
tweaking is possible by adding "(tweakable)" to the first line of the
stack window.)
** How do I return a value from the current stack frame different to what the evaluator has calculated?
You have to be at the normal exit of the relevant frame first, so if
GDS is not already showing you the normally calculated return value,
type `o' to finish the evaluation of the selected frame.
Then type `t' followed by the value you want to return, and <RET>.
The value that you type can be any expression, but note that it will
not be evaluated before being returned; for example if you type `(+ 2
3)', the return value will be a three-element list, not 5.
Finally type one of the commands that tells Guile to continue
execution.
(Tweaking return values, as described here, is only supported by the
latest CVS version of Guile. The GDS stack display tells you when
tweaking is possible by adding "(tweakable)" to the first line of the
stack window.)
** How do I step over a line of code?
Scheme isn't organized by lines, so it doesn't really make sense to
think of stepping over lines. Instead please see the next entry on
stepping over expressions.
** How do I step over an expression?
It depends what you mean by "step over". If you mean that you want
Guile to evaluate that expression normally, but then show you its
return value, type `o', which does exactly that.
If you mean that you want to skip the evaluation of that expression
(for example because it has side effects that you don't want to
happen), use `t' to change the expression to something else which
Guile will evaluate instead.
There has to be a substitute expression so Guile can calculate a value
to return to the calling frame. If you know at a particular point
that the return value is not important, you can type `t #f <RET>' or
`t 0 <RET>'.
See `How do I change the expression that Guile is about to evaluate?'
above for more on using `t'.
** How do I move up and down the call stack?
Type `u' to move up and `d' to move down. "Up" in GDS means to a more
"inner" frame, and "down" means to a more "outer" frame.
** How do I run until the next breakpoint?
Type `g' (for "go").
** How do I run until the end of the selected stack frame?
Type `o'.
** How do I set a breakpoint?
First identify the code that you want to set the breakpoint in, and
what kind of breakpoint you want. To set a breakpoint on entry to a
top level procedure, move the cursor to anywhere in the procedure
definition, and make sure that the region/mark is inactive. To set a
breakpoint on a particular expression (or sequence of expressions) set
point and mark so that the region covers the opening parentheses of
all the target expressions.
Then type ...
`C-c C-b d' for a `debug' breakpoint, which means that GDS will
display the stack when the breakpoint is hit
`C-c C-b t' for a `trace' breakpoint, which means that the start and
end of the relevant procedure or expression(s) will be traced to the
*GDS Trace* buffer
`C-c C-b T' for a `trace-subtree' breakpoint, which means that every
evaluation step involved in the evaluation of the relevant procedure
or expression(s) will be traced to the *GDS Trace* buffer.
You can also type `C-x <SPC>', which does the same as one of the
above, depending on the value of `gds-default-breakpoint-type'.
** How do I clear a breakpoint?
Select a region containing the breakpoints that you want to clear, and
type `C-c C-b <DEL>'.
** How do I trace calls to a particular procedure or evaluations of a particular expression?
In GDS this means setting a breakpoint whose type is `trace' or
`trace-subtree'. See `How do I set a breakpoint?' above.
* Development
** How can I follow or contribute to guile-debugging's development?
guile-debugging is hosted at http://gna.org, so please see the project
page there. Feel free to raise bugs, tasks containing patches or
feature requests, and so on. You can also write directly to me by
email: <neil@ossau.uklinux.net>.
Local Variables:
mode: outline
End:

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;; Test utility code.
(defun gds-test-execute-keys (keys &optional keys2)
(execute-kbd-macro (apply 'vector (listify-key-sequence keys))))
(defvar gds-test-expecting nil)
(defun gds-test-protocol-hook (form)
(message "[protocol: %s]" (car form))
(if (eq (car form) gds-test-expecting)
(setq gds-test-expecting nil)))
(defun gds-test-expect-protocol (proc &optional timeout)
(message "[expect: %s]" proc)
(setq gds-test-expecting proc)
(while gds-test-expecting
(or (accept-process-output gds-debug-server (or timeout 5))
(error "Timed out after %ds waiting for %s" (or timeout 5) proc))))
(defun gds-test-check-buffer (name &rest strings)
(let ((buf (or (get-buffer name) (error "No %s buffer" name))))
(save-excursion
(set-buffer buf)
(goto-char (point-min))
(while strings
(search-forward (car strings))
(setq strings (cdr strings))))))
(defun TEST (desc)
(message "TEST: %s" desc))
;; Make sure we take GDS elisp code from this code tree.
(setq load-path (cons (concat default-directory "emacs/") load-path))
;; Protect the tests so we can do some cleanups in case of error.
(unwind-protect
(progn
;; Visit the tutorial.
(find-file "gds-tutorial.txt")
(TEST "Load up GDS.")
(search-forward "(require 'gds)")
(setq load-path (cons (concat default-directory "emacs/") load-path))
(gds-test-execute-keys "\C-x\C-e")
;; Install our testing hook.
(add-hook 'gds-protocol-hook 'gds-test-protocol-hook)
(TEST "Help.")
(search-forward "(list-ref")
(backward-char 2)
(gds-test-execute-keys "\C-hg\C-m")
(gds-test-expect-protocol 'eval-results 10)
(gds-test-check-buffer "*Guile Help*"
"help list-ref"
"is a primitive procedure in the (guile) module")
(TEST "Completion.")
(re-search-forward "^with-output-to-s")
(gds-test-execute-keys "\e\C-i")
(beginning-of-line)
(or (looking-at "with-output-to-string")
(error "Expected completion `with-output-to-string' failed"))
(TEST "Eval defun.")
(search-forward "(display z)")
(gds-test-execute-keys "\e\C-x")
(gds-test-expect-protocol 'eval-results)
(gds-test-check-buffer "*Guile Evaluation*"
"(let ((x 1) (y 2))"
"Arctangent is: 0.46"
"=> 0.46")
(TEST "Multiple values.")
(search-forward "(values 'a ")
(gds-test-execute-keys "\e\C-x")
(gds-test-expect-protocol 'eval-results)
(gds-test-check-buffer "*Guile Evaluation*"
"(values 'a"
"hello world"
"=> a"
"=> b"
"=> c")
(TEST "Eval region with multiple expressions.")
(search-forward "(display \"Arctangent is: \")")
(beginning-of-line)
(push-mark nil nil t)
(forward-line 3)
(gds-test-execute-keys "\C-c\C-r")
(gds-test-expect-protocol 'eval-results)
(gds-test-check-buffer "*Guile Evaluation*"
"(display \"Arctangent is"
"Arctangent is:"
"=> no (or unspecified) value"
"ERROR: Unbound variable: z"
"=> error-in-evaluation"
"Evaluating expression 3"
"=> no (or unspecified) value")
(TEST "Eval syntactically unbalanced region.")
(search-forward "(let ((z (atan x y)))")
(beginning-of-line)
(push-mark nil nil t)
(forward-line 4)
(gds-test-execute-keys "\C-c\C-r")
(gds-test-expect-protocol 'eval-results)
(gds-test-check-buffer "*Guile Evaluation*"
"(let ((z (atan"
"Reading expressions to evaluate"
"ERROR"
"end of file"
"=> error-in-read")
(TEST "Stepping through an evaluation.")
(search-forward "(for-each (lambda (x)")
(forward-line 1)
(push-mark nil nil t)
(forward-line 1)
(gds-test-execute-keys "\C-u\e\C-x")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys " ")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "o")
(gds-test-expect-protocol 'stack)
(gds-test-execute-keys "g")
(gds-test-expect-protocol 'eval-results)
(gds-test-check-buffer "*Guile Evaluation*"
"(for-each (lambda"
"Evaluating in current module"
"3 cubed is 27"
"=> no (or unspecified) value")
;; Done.
(message "====================================")
(message "gds-test.el completed without errors")
(message "====================================")
)
(switch-to-buffer "gds-debug")
(write-region (point-min) (point-max) "gds-test.debug")
(switch-to-buffer "*GDS Transcript*")
(write-region (point-min) (point-max) "gds-test.transcript")
)

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#!/bin/sh
GUILE_LOAD_PATH=$(pwd) emacs --batch --no-site-file -q -l gds-test.el < gds-test.stdin

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;; Welcome to the GDS tutorial!
;; This tutorial teaches the use of GDS by leading you through a set
;; of examples where you actually use GDS, in Emacs, along the way.
;; To get maximum benefit, therefore, you should be reading this
;; tutorial in Emacs.
;; ** GDS setup
;; The first thing to do, if you haven't already, is to load the GDS
;; library into Emacs. The Emacs Lisp expression for this is:
(require 'gds)
;; So, if you don't already have this in your .emacs, either add it
;; and then restart Emacs, or evaluate it just for this Emacs session
;; by moving the cursor to just after the closing parenthesis and
;; typing `C-x C-e'.
;; (Note that if you _have_ already loaded GDS, and you type `C-x C-e'
;; after this expression, you will see a *Guile Evaluation* window
;; telling you that the evaluation failed because `require' is
;; unbound. Don't worry; this is not a problem, and the rest of the
;; tutorial should still work just fine.)
;; ** Help
;; GDS makes it easy to access the Guile help system when working on a
;; Scheme program in Emacs. For example, suppose that you are writing
;; code that uses list-ref, and need to remind yourself about
;; list-ref's arguments ...
(define (penultimate l)
(list-ref
;; Just place the cursor on the word "list-ref" and type `C-h g RET'.
;; Try it now!
;; If GDS is working correctly, a window should have popped up above
;; or below showing the Guile help for list-ref.
;; You can also do an "apropos" search through Guile's help. If you
;; couldn't remember the name list-ref, for example, you could search
;; for anything matching "list" by typing `C-h C-g' and entering
;; "list" at the minibuffer prompt. Try doing this now: you should
;; see a longish list of Guile definitions whose names include "list".
;; As usual in Emacs, you can use `M-PageUp' and `M-PageDown' to
;; conveniently scroll the other window without having to select it.
;; The functions called by `C-h g' and `C-h C-g' are gds-help-symbol
;; and gds-apropos. They both look up the symbol or word at point by
;; default, but that default can be overidden by typing something else
;; at the minibuffer prompt.
;; ** Completion
;; As you are typing Scheme code, you can ask GDS to complete the
;; symbol before point for you, by typing `ESC TAB'. GDS selects
;; possible completions by matching the text so far against all
;; definitions in the Guile environment. (This may be contrasted with
;; the "dabbrev" completion performed by `M-/', which selects possible
;; completions from the contents of Emacs buffers. So, if you are
;; trying to complete "with-ou", to get "with-output-to-string", for
;; example, `ESC TAB' will always work, because with-output-to-string
;; is always defined in Guile's default environment, whereas `M-/'
;; will only work if one of Emacs's buffers happens to contain the
;; full name "with-output-to-string".)
;; To illustrate the idea, here are some partial names that you can
;; try completing. For each one, move the cursor to the end of the
;; line and type `ESC TAB' to try to complete it.
list-
with-ou
with-output-to-s
mkst
;; (If you are not familiar with any of the completed definitions,
;; feel free to use `C-h g' to find out about them!)
;; ** Evaluation
;; GDS provides several ways for you to evaluate Scheme code from
;; within Emacs.
;; Just like in Emacs Lisp, a single expression in a buffer can be
;; evaluated using `C-x C-e' or `C-M-x'. For `C-x C-e', the
;; expression is that which ends immediately before point (so that it
;; is useful for evaluating something just after you have typed it).
;; For `C-M-x', the expression is the "top level defun" around point;
;; this means the balanced chunk of code around point whose opening
;; parenthesis is in column 0.
;; Take this code fragment as an example:
(let ((x 1) (y 2))
(let ((z (atan x y)))
(display "Arctangent is: ")
(display z)
(newline)
z))
;; If you move the cursor to the end of the (display z) line and type
;; `C-x C-e', the code evaluated is just "(display z)", which normally
;; produces an error, because z is not defined in the usual Guile
;; environment. If, however, you type `C-M-x' with the cursor in the
;; same place, the code evaluated is the whole "(let ((x 1) (y 2))
;; ...)" kaboodle, because that is the most recent expression before
;; point that starts in column 0.
;; Try these now. The Guile Evaluation window should pop up again,
;; and show you:
;; - the expression that was evaluated (probably abbreviated)
;; - the module that it was evaluated in
;; - anything that the code wrote to its standard output
;; - the return value(s) of the evaluation.
;; Following the convention of the Emacs Lisp and Guile manuals,
;; return values are indicated by the symbol "=>".
;; To see what happens when an expression has multiple return values,
;; try evaluating this one:
(values 'a (begin (display "hello world\n") 'b) 'c)
;; You can also evaluate a region of a buffer using `C-c C-r'. If the
;; code in the region consists of multiple expressions, GDS evaluates
;; them sequentially. For example, try selecting the following three
;; lines and typing `C-c C-r'.
(display "Arctangent is: ")
(display z)
(newline)
;; If the code in the region evaluated isn't syntactically balanced,
;; GDS will indicate a read error, for example for this code:
(let ((z (atan x y)))
(display "Arctangent is: ")
(display z)
(newline)
;; Finally, if you want to evaluate something quickly that is not in a
;; buffer, you can use `C-c C-e' and type the code to evaluate at the
;; minibuffer prompt. The results are popped up in the same way as
;; for code from a buffer.
;; ** Breakpoints
;; Before evaluating Scheme code from an Emacs buffer, you may want to
;; set some breakpoints in it. With GDS you can set breakpoints in
;; Scheme code by typing `C-x SPC'.
;;
;; To see how this works, select the second line of the following code
;; (the `(format ...)' line) and type `C-x SPC'.
(for-each (lambda (x)
(format #t "~A cubed is ~A\n" x (* x x x)))
(iota 6))
;; The two opening parentheses in that line should now be highlighted
;; in red, to show that breakpoints have been set at the start of the
;; `(format ...)' and `(* x x x)' expressions. Then evaluate the
;; whole for-each expression by typing `C-M-x' ...
;;
;; In the upper half of your Emacs, a buffer appears showing you the
;; Scheme stack.
;;
;; In the lower half, the `(format ...)' expression is highlighted.
;;
;; What has happened is that Guile started evaluating the for-each
;; code, but then hit the breakpoint that you set on the start of the
;; format expression. Guile therefore pauses the evaluation at that
;; point and passes the stack (which encapsulates everything that is
;; interesting about the state of Guile at that point) to GDS. You
;; can then explore the stack and decide how to tell Guile to
;; continue.
;;
;; - If you move your mouse over any of the identifiers in the
;; highlighted code, a help echo (or tooltip) will appear to tell
;; you that identifier's current value. (Note though that this only
;; works when the stack buffer is selected. So if you have switched
;; to this buffer in order to scroll down and read these lines, you
;; will need to switch back to the stack buffer before trying this
;; out.)
;;
;; - In the stack buffer, the "=>" on the left shows you that the top
;; frame is currently selected. You can move up and down the stack
;; by pressing the up and down arrows (or `u' and `d'). As you do
;; this, GDS will change the highlight in the lower window to show
;; the code that corresponds to the selected stack frame.
;;
;; - You can evaluate an arbitrary expression in the local environment
;; of the selected stack frame by typing `e' followed by the
;; expression.
;;
;; - You can show various bits of information about the selected frame
;; by typing `I', `A' and `S'. Feel free to try these now, to see
;; what they do.
;;
;; You also have control over the continuing evaluation of this code.
;; Here are some of the things you can do - please try them as you
;; read.
;;
;; - `g' tells Guile to continue execution normally. In this case
;; that means that evaluation will continue until it hits the next
;; breakpoint, which is on the `(* x x x)' expression.
;;
;; - `SPC' tells Guile to continue until the next significant event in
;; the same source file as the selected frame. A "significant
;; event" means either beginning to evaluate an expression in the
;; relevant file, or completing such an evaluation, in which case
;; GDS tells you the value that it is returning. Pressing `SPC'
;; repeatedly is a nice way to step through all the details of the
;; code in a given file, but stepping over calls that involve code
;; from other files.
;;
;; - `o' tells Guile to continue execution until the selected stack
;; frame completes, and then to show its return value.
;; Local Variables:
;; mode: scheme
;; End: