[Issue 423] New: dmd ignores empty commandline arguments

Oct 10, 2006

d-bugmail

Oct 10, 2006

Oct 10, 2006

Oct 10, 2006

Oct 10, 2006

Oct 11, 2006

Oct 11, 2006

Oct 12, 2006

Oct 12, 2006

Jun 25, 2008

Jul 10, 2008

http://d.puremagic.com/issues/show_bug.cgi?id=423 Summary: dmd ignores empty commandline arguments Product: D Version: 0.169 Platform: PC OS/Version: Linux Status: NEW Severity: normal Priority: P2 Component: DMD AssignedTo: bugzilla@digitalmars.com ReportedBy: thomas-dloop@kuehne.cn dmd "" a.d is interpreted as >dmd a.d< dmd '' is interpteted as >dmd< --

d-bugmail@puremagic.com wrote: > http://d.puremagic.com/issues/show_bug.cgi?id=423 > > Summary: dmd ignores empty commandline arguments > Product: D > Version: 0.169 > Platform: PC > OS/Version: Linux > Status: NEW > Severity: normal > Priority: P2 > Component: DMD > AssignedTo: bugzilla@digitalmars.com > ReportedBy: thomas-dloop@kuehne.cn > > > dmd "" a.d > is interpreted as >dmd a.d< > > dmd '' > is interpteted as >dmd< That's what it's supposed to do.

On Tue, 10 Oct 2006 01:39:01 -0700, Walter Bright wrote: > d-bugmail@puremagic.com wrote: >> http://d.puremagic.com/issues/show_bug.cgi?id=423 >> >> Summary: dmd ignores empty commandline arguments >> Product: D >> Version: 0.169 >> Platform: PC >> OS/Version: Linux >> Status: NEW >> Severity: normal >> Priority: P2 >> Component: DMD >> AssignedTo: bugzilla@digitalmars.com >> ReportedBy: thomas-dloop@kuehne.cn >> >> dmd "" a.d >> is interpreted as >dmd a.d< >> >> dmd '' >> is interpteted as >dmd< > > That's what it's supposed to do. Why? I would have expected a string of length zero to be passed. -- Derek Parnell Melbourne, Australia "Down with mediocrity!"

Derek Parnell wrote: > On Tue, 10 Oct 2006 01:39:01 -0700, Walter Bright wrote: > >> d-bugmail@puremagic.com wrote: >>> http://d.puremagic.com/issues/show_bug.cgi?id=423 >>> >>> Summary: dmd ignores empty commandline arguments >>> Product: D >>> Version: 0.169 >>> Platform: PC >>> OS/Version: Linux >>> Status: NEW >>> Severity: normal >>> Priority: P2 >>> Component: DMD >>> AssignedTo: bugzilla@digitalmars.com >>> ReportedBy: thomas-dloop@kuehne.cn >>> >>> dmd "" a.d >>> is interpreted as >dmd a.d< >>> >>> dmd '' >>> is interpteted as >dmd< >> That's what it's supposed to do. > > Why? I would have expected a string of length zero to be passed. > So? It's zero-length string is "nothing", hence ignored.

October 10, 2006

Re: [Issue 423] New: dmd ignores empty commandline arguments

Posted by Derek Parnell
in reply to Hasan Aljudy

Permalink

Derek Parnell

Posted in reply to Hasan Aljudy

Permalink

On Tue, 10 Oct 2006 16:47:34 -0600, Hasan Aljudy wrote:

> Derek Parnell wrote:
>> On Tue, 10 Oct 2006 01:39:01 -0700, Walter Bright wrote:
>> 
>>> d-bugmail@puremagic.com wrote:
>>>> http://d.puremagic.com/issues/show_bug.cgi?id=423
>>>>
>>>>            Summary: dmd ignores empty commandline arguments
>>>>            Product: D
>>>>            Version: 0.169
>>>>           Platform: PC
>>>>         OS/Version: Linux
>>>>             Status: NEW
>>>>           Severity: normal
>>>>           Priority: P2
>>>>          Component: DMD
>>>>         AssignedTo: bugzilla@digitalmars.com
>>>>         ReportedBy: thomas-dloop@kuehne.cn
>>>>
>>>> dmd "" a.d
>>>> is interpreted as >dmd a.d<
>>>>
>>>> dmd ''
>>>> is interpteted as >dmd<
>>> That's what it's supposed to do.
>> 
>> Why? I would have expected a string of length zero to be passed.
>> 
> 
> So? It's zero-length string is "nothing", hence ignored.

Huh?   If I hold a cup of coffee, then drink it all, do I still hold nothing or a cup of nothing? A string is a container that holds zero or more characters, IMHO. An empty string is still a string, it just has no characters in it. Consider a blank sheet of paper; is it full of 'space' characters or does it contain nothing? Is it still a page if it has no characters in it? Consider an array of text lines; if one or more of them are empty, do we ignore those when printing on a page or do we use that information?

The strings on a command line contain information even if one of them is empty - at the very least it is a placeholder.

An empty string is different from a string that is not initialized and different again from non-existent 'string'.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocrity!"
11/10/2006 9:07:12 AM

Derek Parnell wrote: > The strings on a command line contain information even if one of them is > empty - at the very least it is a placeholder. We could argue this till the cows come home. But the current behavior: 1) Is a result of the Digital Mars C startup code 2) It's been that way for 20+ years 3) It's embedded into every DM tool and every command line program created with DM Nobody has ever complained about it or even commented on it before. I doubt anyone has noticed it - I certainly haven't, and I've used this stuff probably more than anyone <g>. Linux, however, does behave the way you suggest - at least the default shell I use does it that way. On the other hand, I've never seen any linux utility that made any mention in its documentation about having any meaning assigned to blank arguments. Trying it on a few just gives errors. In other words, I don't think it's worth arguing about or changing.

Walter Bright schrieb am 2006-10-11: > Derek Parnell wrote: >> The strings on a command line contain information even if one of them is empty - at the very least it is a placeholder. > > We could argue this till the cows come home. But the current behavior: > > 1) Is a result of the Digital Mars C startup code > 2) It's been that way for 20+ years > 3) It's embedded into every DM tool and every command line program > created with DM Please document this behaviour(http://www.digitalmars.com/d/dcompiler.html). > Nobody has ever complained about it or even commented on it before. I doubt anyone has noticed it - I certainly haven't, and I've used this stuff probably more than anyone <g>. > > Linux, however, does behave the way you suggest - at least the default shell I use does it that way. On the other hand, I've never seen any linux utility that made any mention in its documentation about having any meaning assigned to blank arguments. Trying it on a few just gives errors. > > In other words, I don't think it's worth arguing about or changing. The Linux Way is very nice for locating scripting bugs: dmd "${SOURCE_1}" "${SPURCE_2}" Thomas

On Thu, 12 Oct 2006 12:58:56 -0600, Hasan Aljudy wrote: > Thomas Kuehne wrote: >> The Linux Way is very nice for locating scripting bugs: >> >> dmd "${SOURCE_1}" "${SPURCE_2}" >> >> Thomas >> > > Hmm, so does it have anything to do with a bug in dbuild, Derek? Huh? Does 'what' have anything to do with dbuild? The topic is about dmd not acknowledging an empty commandline argument. The dbuild utility, having been compiled by dmd, inherits Walter's view of what is correct commandline parsing and it just gets whatever dmd takes out of the command line. So the short answer is *no*. -- Derek Parnell Melbourne, Australia "Down with mediocrity!"

Forums