prin1-to-string noescape parameter

prin1-to-string noescape parameter

[Oleh Krehel]

Hi all,

I'm trying to write some code that formats/restructures Elisp source
files (a la Paredit).  But instead of using text manipulation,
I want to read the object in, manipulate it and print it
out.

One issue that I'm facing is:

    (prin1-to-string (read "(foo.bar baz?)"))
    => "(foo\\.bar baz\\?)"

I tried to overcome this with:

    (prin1-to-string (read "(foo.bar baz?)") t)
    => "(foo.bar baz?)"

But another problem resurfaces instead:

    (prin1-to-string (read "(foo \"bar\")") t)
    => "(foo bar)"

Even worse:

     (prin1-to-string (read "(foo \";bar\")") t)
     => "(foo ;bar)"

I think a fix to the issue would be to split the `escapeflag'
parameter of the `print_object' C function into two parts. Currently a
single bool flag decides if to escape strings or not, and if to escape
certain characters or not.

Any other suggestions to overcome this issue are welcome as well, so
far I've tried setting `print-quoted', `print-escape-multibyte', and
`print-escape-nonascii'.

regards,
Oleh

Re: prin1-to-string noescape parameter

[Andreas Schwab]

Oleh Krehel <oleh.krehel@gmail.com> writes:

> One issue that I'm facing is:
>
>     (prin1-to-string (read "(foo.bar baz?)"))
>     => "(foo\\.bar baz\\?)"

Why is that an issue?  The strings represent objects that will compare
equal.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: prin1-to-string noescape parameter

[Oleh Krehel]

Hi Andreas,

>> One issue that I'm facing is:
>>
>>     (prin1-to-string (read "(foo.bar baz?)"))
>>     => "(foo\\.bar baz\\?)"
>
> Why is that an issue?  The strings represent objects that will compare
> equal.

The issue is that if I have `foo.bar` in the code, and then I re-format
my code by:

- read text
- delete text
- manipulate lisp object
- insert manipulated lisp object

And now my code contains `foo\.bar`, although I don't want it.

regards,
Oleh

Re: prin1-to-string noescape parameter

[Andreas Schwab]

Oleh Krehel <o.krehel@tue.nl> writes:

> The issue is that if I have `foo.bar` in the code, and then I re-format
> my code by:
>
> - read text
> - delete text
> - manipulate lisp object
> - insert manipulated lisp object
>
> And now my code contains `foo\.bar`, although I don't want it.

By passing the text through the lisp reading you are discarding all
redundancy, so it is impossible in general to get back the original
representation.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: prin1-to-string noescape parameter

[Oleh Krehel]

>> The issue is that if I have `foo.bar` in the code, and then I re-format
>> my code by:
>>
>> - read text
>> - delete text
>> - manipulate lisp object
>> - insert manipulated lisp object
>>
>> And now my code contains `foo\.bar`, although I don't want it.
>
> By passing the text through the lisp reading you are discarding all
> redundancy, so it is impossible in general to get back the original
> representation.

Not possible in general, but the thing that I want can be done
by changing slightly the condition at line 240 of print.c

There are already `print_escape_newlines', `print_escape_multibyte' etc.,
so I propose to add one more that makes these tricky chars in symbols be
not quoted.

regards,
Oleh

Re: prin1-to-string noescape parameter

[Andreas Schwab]

Oleh Krehel <o.krehel@tue.nl> writes:

>>> The issue is that if I have `foo.bar` in the code, and then I re-format
>>> my code by:
>>>
>>> - read text
>>> - delete text
>>> - manipulate lisp object
>>> - insert manipulated lisp object
>>>
>>> And now my code contains `foo\.bar`, although I don't want it.
>>
>> By passing the text through the lisp reading you are discarding all
>> redundancy, so it is impossible in general to get back the original
>> representation.
>
> Not possible in general, but the thing that I want can be done
> by changing slightly the condition at line 240 of print.c

No, you can't.  You have already discarded all necessary information.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: prin1-to-string noescape parameter

[Oleh Krehel]

>>>> The issue is that if I have `foo.bar` in the code, and then I re-format
>>>> my code by:
>>>>
>>>> - read text
>>>> - delete text
>>>> - manipulate lisp object
>>>> - insert manipulated lisp object
>>>>
>>>> And now my code contains `foo\.bar`, although I don't want it.
>>>
>>> By passing the text through the lisp reading you are discarding all
>>> redundancy, so it is impossible in general to get back the original
>>> representation.
>>
>> Not possible in general, but the thing that I want can be done
>> by changing slightly the condition at line 240 of print.c
>
> No, you can't.  You have already discarded all necessary information.

Of course it's possible.
Since `foo.bar' and `foo\.bar' is the same symbol, why not
print it as "foo.bar" always? It looks better like this
in the source code anyway, and the reader has no problem with it.

regards,
Oleh

Re: prin1-to-string noescape parameter

[Andreas Schwab]

Oleh Krehel <o.krehel@tue.nl> writes:

> Since `foo.bar' and `foo\.bar' is the same symbol, why not
> print it as "foo.bar" always?

That will not solve your problem.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: prin1-to-string noescape parameter

[Stefan Monnier]

>     (prin1-to-string (read "(foo.bar baz?)"))
>     => "(foo\\.bar baz\\?)"

BTW, for that kind of reason, "." and "?" are not recommended in
Elisp identifiers.


        Stefan