elisp questions for Advanced Closing brackets function

elisp questions for Advanced Closing brackets function

[TheLonelyStar]

Hi,

I have funtions in my .emacs, which inserts "[]" when one types "[" (and
same for "(" and "{").
I also have functions which just jumps over a "]" when "]" is typed.
I want to make this function more advanced!
It should do the following:
When one types "]" it looks for the next character which is NOT a
whitespace. If it is "]", the functions just jumps after this. Otherwise it
inserts an "]".
I am just lerning elisp (just for this), but I am stuck.
My Problems:
- How do I check if the character under (point) is a whitespace?
- In an "if" statement, how do I put more than one expression into the else
case? Like this:
(if condition (do-if-case) ((do-else-case) (do-more-else-case))
- If I have a funcion like this:
(defun adanced-closing-bracket (arg)
  ...)
How do I compare (arg) to the character under point?

Thanks for any help!
Nathan
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RE: elisp questions for Advanced Closing brackets function

[Drew Adams]

> - How do I check if the character under (point) is a whitespace?

See function `looking-at'.

> - In an "if" statement, how do I put more than one expression 
> into the else case? Like this:
> (if condition (do-if-case) ((do-else-case) (do-more-else-case))

Just drop the parens around the else-case parts.

(if (some-test)
    (the-then-part)
  (an-else-part)
  (another-else-part)
  (and-another))

`if' allows any number of sexps in the else part. See also `cond' and `when'.

> - If I have a funcion like this:
> (defun adanced-closing-bracket (arg) ...)
> How do I compare (arg) to the character under point?

You can compare characters with `eq'. `char-after' picks up the character at a
given buffer position.

(eq arg (char-after (point)))

The onboard Elisp manual is your friend.
See also the onboard manual "Emacs Lisp Intro".

RE: elisp questions for Advanced Closing brackets function

[TheLonelyStar]

Hi,

Thanks for your help! I am sorry if I should have found this information in
the manual.
What do you mean by the "onboard elisp manual"?
This:
http://www.gnu.org/software/emacs/manual/elisp.html ?

I have a another question for which I did not find an answer in the link
above:
I want the closing-parentese function to be more general.
I want to call the same funciton for "]", ")" and "}".
So i would bind this function to all these keys.
But how can the function know by which key it was invoked?
I thought, the key would be given as argument ... but if it is I do not know
how to format the argument to the correct character.

Thanks!
Nathan


Drew Adams wrote:
> 
>> - How do I check if the character under (point) is a whitespace?
> 
> See function `looking-at'.
> 
>> - In an "if" statement, how do I put more than one expression 
>> into the else case? Like this:
>> (if condition (do-if-case) ((do-else-case) (do-more-else-case))
> 
> Just drop the parens around the else-case parts.
> 
> (if (some-test)
>     (the-then-part)
>   (an-else-part)
>   (another-else-part)
>   (and-another))
> 
> `if' allows any number of sexps in the else part. See also `cond' and
> `when'.
> 
>> - If I have a funcion like this:
>> (defun adanced-closing-bracket (arg) ...)
>> How do I compare (arg) to the character under point?
> 
> You can compare characters with `eq'. `char-after' picks up the character
> at a
> given buffer position.
> 
> (eq arg (char-after (point)))
> 
> The onboard Elisp manual is your friend.
> See also the onboard manual "Emacs Lisp Intro".
> 
> 
> 
> 
> 

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RE: elisp questions for Advanced Closing brackets function

[Drew Adams]

> What do you mean by the "onboard elisp manual"?
> This: http://www.gnu.org/software/emacs/manual/elisp.html ?

Yes, but by "onboard" I meant that it is also part of Emacs itself. Use `C-h i'
in Emacs to access all of the onboard manuals. Start with the Info manual, which
explains how to use this help system.

"On board" might not be the official terminology, but "online" seems to imply a
network or Internet connection these days. Whatever the terminology, this is
Info, the hypertext (online) help system which is built into Emacs (in addition
to sometimes standing alone).

> I have a another question for which I did not find an answer 
> in the link above:
> I want the closing-parentese function to be more general.
> I want to call the same funciton for "]", ")" and "}".
> So i would bind this function to all these keys.
> But how can the function know by which key it was invoked?

Look up `this-command-keys' in the Elisp manual. Or search the code in the
`lisp' directory of your Emacs installation, to see how it can be used.

> I thought, the key would be given as argument ... but if it 
> is I do not know how to format the argument to the correct character.

Re: elisp questions for Advanced Closing brackets function

[Pierre Lorenzon]

Hi Nathan,

I hvae two suggestions which are not very precise : excuse me
for that ! 

1. First have a look at all the already developped lisp code :
there's maybe what you need or something very near.

2. If you absolutely want to implement it by yourself (which
can be very instructive), I'll suggest to look at the regexp
manipulations in emacs-lisp. I suspect that some of the
functions you try to implement might be shorter, simpler and
faster just using regexp. I would not be surprised as well that
some of your question could be solved in terms of syntax
tables.

Regards

Pierre


From: TheLonelyStar <nabble@lonely-star.org>
Subject: RE: elisp questions for Advanced Closing brackets function
Date: Tue, 20 May 2008 13:04:14 -0700 (PDT)

> 
> Hi,
> 
> Thanks for your help! I am sorry if I should have found this information in
> the manual.
> What do you mean by the "onboard elisp manual"?
> This:
> http://www.gnu.org/software/emacs/manual/elisp.html ?
> 
> I have a another question for which I did not find an answer in the link
> above:
> I want the closing-parentese function to be more general.
> I want to call the same funciton for "]", ")" and "}".
> So i would bind this function to all these keys.
> But how can the function know by which key it was invoked?
> I thought, the key would be given as argument ... but if it is I do not know
> how to format the argument to the correct character.
> 
> Thanks!
> Nathan
> 
> 
> Drew Adams wrote:
> > 
> >> - How do I check if the character under (point) is a whitespace?
> > 
> > See function `looking-at'.
> > 
> >> - In an "if" statement, how do I put more than one expression 
> >> into the else case? Like this:
> >> (if condition (do-if-case) ((do-else-case) (do-more-else-case))
> > 
> > Just drop the parens around the else-case parts.
> > 
> > (if (some-test)
> >     (the-then-part)
> >   (an-else-part)
> >   (another-else-part)
> >   (and-another))
> > 
> > `if' allows any number of sexps in the else part. See also `cond' and
> > `when'.
> > 
> >> - If I have a funcion like this:
> >> (defun adanced-closing-bracket (arg) ...)
> >> How do I compare (arg) to the character under point?
> > 
> > You can compare characters with `eq'. `char-after' picks up the character
> > at a
> > given buffer position.
> > 
> > (eq arg (char-after (point)))
> > 
> > The onboard Elisp manual is your friend.
> > See also the onboard manual "Emacs Lisp Intro".
> > 
> > 
> > 
> > 
> > 
> 
> -- 
> View this message in context: http://www.nabble.com/elisp-questions-for-Advanced-Closing-brackets-function-tp17346961p17349504.html
> Sent from the Emacs - Help mailing list archive at Nabble.com.
> 
> 
> 

Re: elisp questions for Advanced Closing brackets function

[Lorenzo Isella]

Dear All,
My questions are even more basic than the ones expressed here.
I would like to do some "trivial" emacs customization.
First of all, I should say I am not a lisp programmer at all and that
my .emacs file
is at the present a patchwork of examples I found online.
Yet, what I would like to do should be quite simple.
A few examples:
(1) I often use auctex, but when I open a tex file I would like to
have pdflatex as
the default, so I would like to skip the tedious C-c C-t C-p.
How can I include this command in the .emacs file? Obviously it should
be executed only when I am opening and reading a .tex file.
(2) Here is something I do not understand.  I found online the
following handy function for automatically inserting another "$" sign
when I type one and moving back the cursor:

   (defun TeX-insert-dollar () "custom redefined insert-dollar" (interactive)
     (insert "$$")       ;in LaTeX mode, typing "$" automatically insert "$$"
     (backward-char 1)) ;and go between them: no more matching problems!

Then, I tried doing something similar when quoting:

   (defun TeX-insert-quote () "custom redefined insert-quote" (interactive)
     (insert "``''")
     (backward-char 2))

and it worked. However, when I tried doing the same with brackets:

   (defun TeX-insert-curly () "custom redefined insert-curly" (interactive)
     (insert "{}")
     (backward-char 1))

I did not get any error message, but it surely does not work on my
system.

Why is that? Is the emacs lisp documentation mentioned in the email I
am quoting the right place to look for answers?
Cheers

Lorenzo



> Message: 5
> Date: Tue, 20 May 2008 11:12:07 -0700 (PDT)
> From: TheLonelyStar <nabble@lonely-star.org>
> Subject: elisp questions for Advanced Closing brackets function
> To: Help-gnu-emacs@gnu.org
> Message-ID: <17346961.post@talk.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
>
> Hi,
>
> I have funtions in my .emacs, which inserts "[]" when one types "[" (and
> same for "(" and "{").
> I also have functions which just jumps over a "]" when "]" is typed.
> I want to make this function more advanced!
> It should do the following:
> When one types "]" it looks for the next character which is NOT a
> whitespace. If it is "]", the functions just jumps after this. Otherwise it
> inserts an "]".
> I am just lerning elisp (just for this), but I am stuck.
> My Problems:
> - How do I check if the character under (point) is a whitespace?
> - In an "if" statement, how do I put more than one expression into the else
> case? Like this:
> (if condition (do-if-case) ((do-else-case) (do-more-else-case))
> - If I have a funcion like this:
> (defun adanced-closing-bracket (arg)
>  ...)
> How do I compare (arg) to the character under point?
>
> Thanks for any help!
> Nathan
> --
> View this message in context: http://www.nabble.com/elisp-questions-for-Advanced-Closing-brackets-function-tp17346961p17346961.html
> Sent from the Emacs - Help mailing list archive at Nabble.com.
>
>
>

Re: elisp questions for Advanced Closing brackets function

[Tim X]

TheLonelyStar <nabble@lonely-star.org> writes:

> Hi,
>
> I have funtions in my .emacs, which inserts "[]" when one types "[" (and
> same for "(" and "{").
> I also have functions which just jumps over a "]" when "]" is typed.
> I want to make this function more advanced!
> It should do the following:
> When one types "]" it looks for the next character which is NOT a
> whitespace. If it is "]", the functions just jumps after this. Otherwise it
> inserts an "]".
> I am just lerning elisp (just for this), but I am stuck.
> My Problems:
> - How do I check if the character under (point) is a whitespace?

Read the emacs lisp reference manual on syntax tables.

> - In an "if" statement, how do I put more than one expression into the else
> case? Like this:
> (if condition (do-if-case) ((do-else-case) (do-more-else-case))

You may be a little confused. The if statement only allows one
expression in the 'if' part, but you can have multiple expressions in
the else part - just put them inside a (). Note also that you should
look at progn. 

Often, lisp style tends to use other conditional constructs when
multiple expressions need to be executed, such as cond. Again, reading
existing code will help you identify the more common idioms.

> - If I have a funcion like this:
> (defun adanced-closing-bracket (arg)
>   ...)
> How do I compare (arg) to the character under point?
>

I'd strongly recommend you read the emacs lisp reference manual and you
may get a bit out of Robert J Chassell's Introduction to Emacs
Lisp. both are now bundled with emacs, but both can be found on the gnu
website. I would also recommend checking out the emacs wiki. 

I realise you are doing much of this as a learning exercise, but I'm not
sure how much you realise you are re-inventing an already overworked
wheel. 

have a look at paredit mode. also, check what features emacs already
has. In many cases all of this stuff is already there and of course,
with source code. You can look at the code an learn a lot of useful
techniques and tricks. 

tim


-- 
tcross (at) rapttech dot com dot au

Re: elisp questions for Advanced Closing brackets function

[Rupert Swarbrick]

"Lorenzo Isella" <lorenzo.isella@gmail.com> writes:

> Dear All,
> My questions are even more basic than the ones expressed here.
> I would like to do some "trivial" emacs customization.
> First of all, I should say I am not a lisp programmer at all and that
> my .emacs file
> is at the present a patchwork of examples I found online.
> Yet, what I would like to do should be quite simple.
> A few examples:
> (1) I often use auctex, but when I open a tex file I would like to
> have pdflatex as
> the default, so I would like to skip the tedious C-c C-t C-p.
> How can I include this command in the .emacs file? Obviously it should
> be executed only when I am opening and reading a .tex file.

Ok, I didn't know the answer to this at first, so here's how I found it:

Firstly, what does C-c C-t C-p run? (I know what it does, but what
function name?) Use C-h c which tells you the name of the function
bound to the given key sequence.

C-h c C-c C-t C-p gives TeX-PDF-mode. Now, what does that do? Well,
let's look at its docs: C-h f TeX-PDF-mode

Gives:

,----
| TeX-PDF-mode is an interactive compiled Lisp function in <long stuff>
| It is bound to C-c C-t C-p.
| (TeX-PDF-mode &optional ARG)
| 
| Minor mode for using PDFTeX.
| 
| If enabled, PDFTeX will be used as an executable by default.
| You can customize an initial value, and you can use the
| function `TeX-global-PDF-mode' for toggling this value.
`----

Ahah! So we want to know about TeX-global-PDF-mode! Roight, let's look
at that function, using C-h f TeX-global-PDF-mode. Well that says:

,----
| TeX-global-PDF-mode is an interactive compiled Lisp func <blah blah>
| (TeX-global-PDF-mode &optional ARG)
| 
| Toggle default for `TeX-PDF-mode'.
`----

(Ye gods, will we ever get there?!) But TeX-PDF-mode is a variable,
which is looking promising. Maybe we can use customise. Finally (!)
call C-h v TeX-PDF-mode and you'll see near the bottom of the help
page a link to customise the variable. Tada!

I realise this is a roundabout way to get the answer, but maybe this
answer will help you solve the next problem you come across.


> (2) Here is something I do not understand.  I found online the
> following handy function for automatically inserting another "$" sign
> when I type one and moving back the cursor:
>
>    (defun TeX-insert-dollar () "custom redefined insert-dollar" (interactive)
>      (insert "$$")       ;in LaTeX mode, typing "$" automatically insert "$$"
>      (backward-char 1)) ;and go between them: no more matching problems!
>
> Then, I tried doing something similar when quoting:
>
>    (defun TeX-insert-quote () "custom redefined insert-quote" (interactive)
>      (insert "``''")
>      (backward-char 2))
>
> and it worked. However, when I tried doing the same with brackets:
>
>    (defun TeX-insert-curly () "custom redefined insert-curly" (interactive)
>      (insert "{}")
>      (backward-char 1))
>
> I did not get any error message, but it surely does not work on my
> system.

What is happening is that you are (successfully) *redefining* the
functions TeX-insert-quote and TeX-insert-dollar, which were
originally defined somewhere in the depths of auctex and bound to the
keys " and $ respectively.

What you need to do is get auctex to run your TeX-insert-curly when
you hit { in the same way. The following should work:

(local-set-key "{" 'TeX-insert-curly)

But it needs to get run whenever you enter tex mode, so you can't just
plonk it in your .emacs (otherwise it would apply to emacs lisp mode,
I think) and instead need to run it on what is called a mode
hook. Since you haven't done much elisp and this is a bit obscure, the
magic incantation to put in your .emacs is

(add-hook 'TeX-mode-hook
          (lambda () (local-set-key "{" 'TeX-insert-curly)))


(after you've defined TeX-insert-curly)


Rupert

Re: elisp questions for Advanced Closing brackets function

[Rupert Swarbrick]

Rupert Swarbrick <rswarbrick@gmail.com> writes:

>
> C-h c C-c C-t C-p gives TeX-PDF-mode. Now, what does that do? Well,
> let's look at its docs: C-h f TeX-PDF-mode
>
> Gives:
>
> ,----
> | TeX-PDF-mode is an interactive compiled Lisp function in <long stuff>
> | It is bound to C-c C-t C-p.
> | (TeX-PDF-mode &optional ARG)
> | 
> | Minor mode for using PDFTeX.
> | 
> | If enabled, PDFTeX will be used as an executable by default.
> | You can customize an initial value, and you can use the
> | function `TeX-global-PDF-mode' for toggling this value.
> `----
>
> Ahah! So we want to know about TeX-global-PDF-mode! Roight, let's look
> at that function, using C-h f TeX-global-PDF-mode. Well that says:
>
> ,----
> | TeX-global-PDF-mode is an interactive compiled Lisp func <blah blah>
> | (TeX-global-PDF-mode &optional ARG)
> | 
> | Toggle default for `TeX-PDF-mode'.
> `----
>
> (Ye gods, will we ever get there?!) But TeX-PDF-mode is a variable,
> which is looking promising. Maybe we can use customise. Finally (!)
> call C-h v TeX-PDF-mode and you'll see near the bottom of the help
> page a link to customise the variable. Tada!
>
> I realise this is a roundabout way to get the answer, but maybe this
> answer will help you solve the next problem you come across.
>

I've just read that again, and realised that I didn't notice we've
seen TeX-PDF-mode twice! But elisp, like many other lisps, uses two
different tables of symbols: one for functions and one for
variables. Which is why C-h f TeX-PDF-mode and C-h v TeX-PDF-mode do
different things. Random, eh?

Anyway, I think I've successfully demonstrated that even if you're a
bit dopey, you can still solve this sort of problem (-:

Rupert

Re: elisp questions for Advanced Closing brackets function

[Ralf Angeli]

* Lorenzo Isella (2008-05-21) writes:

>    (defun TeX-insert-dollar () "custom redefined insert-dollar" (interactive)
[...]
>    (defun TeX-insert-quote () "custom redefined insert-quote" (interactive)

You are lobotomizing AUCTeX bit by bit.

-- 
Ralf

Re: elisp questions for Advanced Closing brackets function

[Rupert Swarbrick]

Ralf Angeli <dev.null@caeruleus.net> writes:

> * Lorenzo Isella (2008-05-21) writes:
>
>>    (defun TeX-insert-dollar () "custom redefined insert-dollar" (interactive)
> [...]
>>    (defun TeX-insert-quote () "custom redefined insert-quote" (interactive)
>
> You are lobotomizing AUCTeX bit by bit.

'tis true. And in fact that's what I immediately thought.... but if
you look at what he wants to happen, the normal TeX-insert-quote and
TeX-insert-dollar don't in fact help him at all. So more power to him!

Rupert

Re: elisp questions for Advanced Closing brackets function

[Ralf Angeli]

* Rupert Swarbrick (2008-05-21) writes:

> Ralf Angeli <dev.null@caeruleus.net> writes:
>
>> * Lorenzo Isella (2008-05-21) writes:
>>
>>>    (defun TeX-insert-dollar () "custom redefined insert-dollar" (interactive)
>> [...]
>>>    (defun TeX-insert-quote () "custom redefined insert-quote" (interactive)
>>
>> You are lobotomizing AUCTeX bit by bit.
>
> 'tis true. And in fact that's what I immediately thought.... but if
> you look at what he wants to happen, the normal TeX-insert-quote and
> TeX-insert-dollar don't in fact help him at all.

Then use them, don't kill them.

-- 
Ralf