Re: Flag atom_no_escape has no effect?

[Yi Dai]

Hi,

Thanks for the quick answer.

On Thu, May 23, 2013 at 4:02 PM, Daniel Diaz <address@hidden> 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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