Hi,

Thanks for the quick answer.

On Thu, May 23, 2013 at 4:02 PM, Daniel Diaz <[email protected]>wrote:

>  Hi,
>
> it is not a bug, the flag controls back quoted tokens, i.e. surrounded
> with a backquote ` not a quote '.
> So you should use:
>
>
> | ?- atom_chars(`\'`, CS).
>
> CS = [\,'''']
>

Ah, obviously I confused single quotes and back quotes.  But is it possible
to disable escape sequences in single quotes too?  If I did not mistake it,
in core prolog, there is only one kind of escape sequence inside single
quotes, namely '' (two single quotes).



> Le 23/05/2013 15:08, Yi Dai a écrit :
>
> Hi,
>
>
>  I am using gprolog 1.4.4.  According to the manual, by default, the flag
> `back_quotes` is set to ` atom_no_escape`, which means no escape sequence
> is supported inside back quotes.  But I surprisingly find that it is not
> the case.  Below is a dialog of an interactive session:
>
>
>  GNU Prolog 1.4.4 (32 bits)
> Compiled Apr 29 2013, 20:41:58 with gcc
> By Daniel Diaz
> Copyright (C) 1999-2013 Daniel Diaz
> | ?- current_prolog_flag(back_quotes, X).
>
>  X = atom_no_escape
>
>  yes
> | ?- atom_chars('''', CS).
>
>  CS = ['''']
>
>  yes
> | ?- atom_chars('\'', CS).
>
>  CS = ['''']
>
>  yes
> | ?- atom_chars('\\', CS).
>
>  CS = [\]
>
>  yes
> | ?- atom_chars('\n', CS).
>
>  CS = ['\n']
>
>  yes
> | ?- atom_chars('\''', CS).
> uncaught exception: error(syntax_error('user_input:6 (char:23) unexpected
> newline'),read_term/3)
>
>
>  Apparently escape sequences are still allowed.  How can I disable it?
>  Note that turning on the flag ` strict_iso` does not help.  Is this a bug?
>
>
>  Regards,
>
>
>  Yi
>
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