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digitalmars.D - Octal-like integer literals

reply "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
Alright, I'm plodding along slowly with my D lexer, and I'm running into
an interesting case. According to the spec, int literals that begin with
'0' are supposed to be octal, with the exception of "0" itself, which is
decimal 0. DecimalInteger is defined to begin with a non-zero digit
followed by one or more digits (may be zero).

So how should the lexer treat a literal like "0800" or "0900"?

(Since octal literals are deprecated, I'm leaving them out of my lexer,
so should 0800 and 0900 be rejected as invalid?)


T

-- 
Change is inevitable, except from a vending machine.
Feb 11 2012
next sibling parent reply "Daniel Murphy" <yebblies nospamgmail.com> writes:
As an error.  Because they're allowed in C/C++/etc having them accepted by D 
but interpreted differently is just errors waiting to happen.

"H. S. Teoh" <hsteoh quickfur.ath.cx> wrote in message 
news:mailman.230.1328975949.20196.digitalmars-d puremagic.com...
 Alright, I'm plodding along slowly with my D lexer, and I'm running into
 an interesting case. According to the spec, int literals that begin with
 '0' are supposed to be octal, with the exception of "0" itself, which is
 decimal 0. DecimalInteger is defined to begin with a non-zero digit
 followed by one or more digits (may be zero).

 So how should the lexer treat a literal like "0800" or "0900"?

 (Since octal literals are deprecated, I'm leaving them out of my lexer,
 so should 0800 and 0900 be rejected as invalid?)


 T

 -- 
 Change is inevitable, except from a vending machine. 
Feb 11 2012
parent Ellery Newcomer <ellery-newcomer utulsa.edu> writes:
OT: http://d.puremagic.com/issues/show_bug.cgi?id=5132

On 02/11/2012 10:06 AM, Daniel Murphy wrote:
  interpreted differently is just errors waiting to happen.
Feb 11 2012
prev sibling parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 02/11/2012 05:00 PM, H. S. Teoh wrote:
 Alright, I'm plodding along slowly with my D lexer, and I'm running into
 an interesting case. According to the spec, int literals that begin with
 '0' are supposed to be octal, with the exception of "0" itself, which is
 decimal 0. DecimalInteger is defined to begin with a non-zero digit
 followed by one or more digits (may be zero).

 So how should the lexer treat a literal like "0800" or "0900"?

 (Since octal literals are deprecated, I'm leaving them out of my lexer,
 so should 0800 and 0900 be rejected as invalid?)


 T
Octal literals whose value is larger than 7 must be rejected. Octal literals with values up to 7 must be accepted.
Feb 11 2012
next sibling parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Sat, Feb 11, 2012 at 05:37:17PM +0100, Timon Gehr wrote:
 On 02/11/2012 05:00 PM, H. S. Teoh wrote:
Alright, I'm plodding along slowly with my D lexer, and I'm running into
an interesting case. According to the spec, int literals that begin with
'0' are supposed to be octal, with the exception of "0" itself, which is
decimal 0. DecimalInteger is defined to begin with a non-zero digit
followed by one or more digits (may be zero).

So how should the lexer treat a literal like "0800" or "0900"?

(Since octal literals are deprecated, I'm leaving them out of my lexer,
so should 0800 and 0900 be rejected as invalid?)
[...]
 
 Octal literals whose value is larger than 7 must be rejected. Octal
 literals with values up to 7 must be accepted.
Are we still supporting octal literals? They are scheduled to be removed at some point, right? FWIW the online specs have no reference to octal literals although the definitions of octal digits are still there. T -- There's light at the end of the tunnel. It's the oncoming train.
Feb 11 2012
prev sibling next sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
Octals are going away, the use of them in Phobos have been removed and
Walter confirmed this too afaik.
Feb 11 2012
prev sibling next sibling parent reply "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Sat, Feb 11, 2012 at 06:48:20PM +0100, Andrej Mitrovic wrote:
 Octals are going away, the use of them in Phobos have been removed and
 Walter confirmed this too afaik.
So the question is, how will things like "0744" and "098" be interpreted once octals have gone away? Will they still be rejected by the compiler? T -- Talk is cheap. Whining is actually free. -- Lars Wirzenius
Feb 11 2012
parent Timon Gehr <timon.gehr gmx.ch> writes:
On 02/11/2012 07:05 PM, H. S. Teoh wrote:
 On Sat, Feb 11, 2012 at 06:48:20PM +0100, Andrej Mitrovic wrote:
 Octals are going away, the use of them in Phobos have been removed and
 Walter confirmed this too afaik.
So the question is, how will things like "0744" and "098" be interpreted once octals have gone away? Will they still be rejected by the compiler? T
Probably yes, except for '0+[1-7]?'.
Feb 11 2012
prev sibling parent reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 2/11/12, H. S. Teoh <hsteoh quickfur.ath.cx> wrote:
 On Sat, Feb 11, 2012 at 06:48:20PM +0100, Andrej Mitrovic wrote:
 Octals are going away, the use of them in Phobos have been removed and
 Walter confirmed this too afaik.
So the question is, how will things like "0744" and "098" be interpreted once octals have gone away? Will they still be rejected by the compiler?
module test; void main() { auto x = 0744; } $ dmd test.d $ test.d(5): octal literals 0744 are deprecated, use std.conv.octal!744 instead You can only use them with the -d switch.
Feb 11 2012
next sibling parent Walter Bright <newshound2 digitalmars.com> writes:
On 2/11/2012 10:43 AM, Andrej Mitrovic wrote:
 You can only use them with the -d switch.
And 0744 will never be valid D code, for the simple reason that code moved over from C would silently break in awful ways.
Feb 16 2012
prev sibling parent reply Walter Bright <newshound2 digitalmars.com> writes:
On 2/11/2012 10:43 AM, Andrej Mitrovic wrote:
 $ dmd test.d
 $ test.d(5): octal literals 0744 are deprecated, use std.conv.octal!744 instead
I was inordinately proud of that error message :-)
Feb 16 2012
parent reply "Daniel Murphy" <yebblies nospamgmail.com> writes:
I had a look at moving them from deprecated to error, but druntime uses them 
extensively in the os headers.  I think we need a better solution than a 
template in the standard library - you shouldn't need a dependency on phobos 
to use them, and the compiler shouldn't directly reference anything in the 
standard library.

"Walter Bright" <newshound2 digitalmars.com> wrote in message 
news:jhkqsj$30j$2 digitalmars.com...
 On 2/11/2012 10:43 AM, Andrej Mitrovic wrote:
 $ dmd test.d
 $ test.d(5): octal literals 0744 are deprecated, use std.conv.octal!744 
 instead
I was inordinately proud of that error message :-)
Feb 16 2012
parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Fri, Feb 17, 2012 at 05:17:00PM +1100, Daniel Murphy wrote:
 I had a look at moving them from deprecated to error, but druntime
 uses them extensively in the os headers.  I think we need a better
 solution than a template in the standard library - you shouldn't need
 a dependency on phobos to use them, and the compiler shouldn't
 directly reference anything in the standard library.
So why not make the octal template part of druntime? --T
 "Walter Bright" <newshound2 digitalmars.com> wrote in message 
 news:jhkqsj$30j$2 digitalmars.com...
 On 2/11/2012 10:43 AM, Andrej Mitrovic wrote:
 $ dmd test.d
 $ test.d(5): octal literals 0744 are deprecated, use std.conv.octal!744 
 instead
I was inordinately proud of that error message :-)
Feb 16 2012