Debugging Perl in Emacs

Notes only:

• http://search.cpan.org/~yewenbin/Emacs-PDE-0.2.16/lib/Emacs/PDE.pm
• http://www.emacswiki.org/emacs/PerlLanguage
• http://www.emacswiki.org/emacs/CPerlMode
• http://cpansearch.perl.org/src/YEWENBIN/Emacs-PDE-0.2.16/lisp/doc/QuickStartEn.html

Emacs for a vi user

In the past I've exclusively used vi, but now I want to use Emacs as I've heard it has some useful modes, for example 'font-lock-keywords' mode which is one way to easily highlight certain keywords in a program's console output. I don't want to mess around compiling specialised text highlighting programs, and they're not in my standard repos. Emacs is much more likely to already be available wherever I need it.

Emacs commands:

• To exit: C-x C-c
• Turn on syntax highlighting: M-x font-lock-mode

Key:

C = Ctrl

M = Meta (Alt)

Thanks to the rest of the web

UPDATE: It turns out font-lock-keywords can easily be implemented in a 3 line bash script. Call it "highlight":

    # Usage: tail -f error.log | highlight "error"
    RED="$(tput setaf 1)"
    RESET="$(tput setaf 7)"
    sed "s/$1/$RED$1$RESET/"

But I would still like to see the Perl debugger integrated into Emacs

Setting up xemacs xslt-process mode

I set all these options in the environment:

#########################
# copied from /etc/java/java.conf
# JPackage Project
#########################
# Location of jar files on the system
export JAVA_LIBDIR=/usr/share/java
# Location of arch-specific jar files on the system
export JNI_LIBDIR=/usr/lib/java
# List of known java homes (used for autodetection if none is provided)
export JAVA_HOME_LIST=$JAVA_LIBDIR-utils/java_home.list
# Root of all JVM installations
export JVM_ROOT=/usr/lib/jvm
# Default jvm
export JAVA_HOME=$JVM_ROOT/java
# Options to pass to the java interpreter
export JAVACMD_OPTS=
#########################

export CLASSPATH=/usr/share/java

Now when I try to run xslt-process, it says:
Starting the BeanShell. Please wait...

...but then straight away it still always says:
Could not process file, most probably (Xalan1|Saxon) could not be found!

What I think is happening:

• xalan-2.4.1.jar is installed, not xalan1 as is required.
• Not all of saxon's dependencies are installed.
• 
  

Working with xemacs XSLT-process mode

M-x xslt-process-mode - enable xslt-process mode
C-c C-x v - run the xslt processor and view results (be sure to type slowly enough!)

M-x customize-group RET xslt-process - options menu: change engine, customise key bindings, etc.

NOTE: the default run command above may have problems under cygwin. Redefine it to C-x C-c C-v and it should work.

xemacs buffer control

C-x b [buffer] [enter] - select or create a named buffer
C-x C-b - list existing buffers
C-x 1 - close the buffer list

Emacs and Cygwin

Can't quit emacs from cygwin?

From within Cygwin, if you start xemacs with: xemacs -nw (for No Window), then C-x C-c to quit emacs does not work. Instead you must type C-g to exit.

xemacs mode line

How to interpret the status line in xemacs:
http://www.xemacs.org/Documentation/21.5/html/xemacs_4.html#SEC10

GNU info

navigate within info screens:

b	go to beginning of the page
?	help
m	choose a menu item from the current page (has tab completion)
f	choose a cross-reference to follow (tab completion)
f?	list all cross-references on the current page
l	go back to last page
Ctrl-g	cancel menu command
i	search index for topic
d	directory of all info pages
t	go to 'top' of current manual
s	search forward
q	quit info screen

Emacs

Emacs is desirable for its XSLT debug mode, Emacs::PDE, and font-lock-keywords mode

Viper is a full-featured Vi emulator for GNU Emacs and XEmacs. But if you don't use that, keep reading.

Emacs notes, from the perspective of a vi user

Problems:

* The manual calls for C-h (Ctrl-h) to be used as a special command
** but when using Putty from Windows, by default Ctrl-h just does a backspace.
** from Windows, it can't tell the difference between Ctrl-H and the backspace key
** This means if you re-map Ctrl-H, it also re-maps the Backspace key. I haven't solved this yet.

--------------------------------------------------------

To read the manual on key commands:

1) type F1, i - gets you to the info menu
2) type m, emacs, [enter] - takes you to the Emacs info file
3) Page down to "Fundamental Editing Commands", "Important Text-Changing Commands", etc. and press [enter] on the menu items you want (typing lowercase L takes you

'back' one page)

--------------------------------------------------------

Notes:

* Terminology: C-x means Ctrl-x, C-M-x means Ctrl-Meta-x - the Meta key is Alt under MS Windows)
* For some commands, holding Ctrl is required for the second character (e.g. quit: C-x, C-c), and for others commands it's not (e.g. undo: C-x u)
* Commands like this "M-x set-visited-file-name" mean: type Meta-x, then type the string 'set-visited-file-name'.
* After typing M-x you can also use tab-completion to find commands.

Translation of common Emacs commands for vi users:

command	vi	emacs
save file	:w	C-x C-s
save & exit read-only file	:wq!	C-x, C-c, follow prompts
save to a different file	:w foo	M-x set-visited-file-name
find a file to open		C-x C-f
delete to end of line	Shift-d	C-k
undo	u	C-x u
	u	C-_ (hold Ctrl, press dash/hypen/underscore key)
redo	r	break out of undo mode, and type C-_ again
note: these searches are case insensitive
search forward	/	C-s (incremental / search-as-you-type)
	/	C-s, [enter] (non incremental / type whole word, then search)
search backward	?	C-r (incremental)
	?	C-r, [enter] (non incremental)
note: even these *regex* searches are case insensitive. There is a way to make them case sensitive: set the variable `case-fold-search' to `nil'.
search forward using regex		C-M-s (incremental)
and backward		C-M-r
call out to the shell	!	M-! (Meta-Shift-1)
start a full subshell		M-x eshell

Notes on differences to vi:

* undo commands wrap around. Once you undo all your edits, the undo command reverses direction and starts re-doing the edits! break out of the undo mode and press C-_ (undo) again to change the direction of undo/redo command.

* files are autosaved to a seperate buffer. to recover after a crash, type: M-x recover-file foo.c


Emacs-only commands:

list commands in help menu	F1, ?
get help on key combinations	F1, k, [some key combination]
toggle read-only status of the buffer	C-x, C-q
get out of a command	C-g
redo an edit (undo the undo)	type any harmless character to break out of undo mode. You will now be able to undo your undo commands.
remove help window	C-x 1
scroll the help	C-M-v
re-map a key	M-x global-set-key [enter]