Tuesday, December 19, 2017

Digest for comp.lang.c++@googlegroups.com - 25 updates in 5 topics

fir <profesor.fir@gmail.com>: Dec 19 10:51AM -0800

W dniu wtorek, 19 grudnia 2017 18:29:00 UTC+1 użytkownik Real Troll napisał:
> the original creator is the best place to start. Ask him/her if you
> could have the source code!!!
 
> Good luck.
 
i ask for laziness.maybe good googling will show it.. dont know yet
fir <profesor.fir@gmail.com>: Dec 19 10:54AM -0800

W dniu wtorek, 19 grudnia 2017 18:22:36 UTC+1 użytkownik red floyd napisał:
> On 12/19/2017 8:28 AM, fir wrote:
> > [OT redacted]
 
> Did you have a C++ language question?
 
i guess it was written in c/c++
(and i dont share the view that this or c
group are only for talking language, if
so and this is c-language where is c-programming group) (i know its c++ but write c for short, i dislike c++ only like when it covers with c ;c)
red floyd <dont.bother@its.invalid>: Dec 19 12:03PM -0800

On 12/19/2017 10:54 AM, fir wrote:
> (and i dont share the view that this or c
> group are only for talking language, if
> so and this is c-language where is c-programming group) (i know its c++ but write c for short, i dislike c++ only like when it covers with c ;c)
 
1. There is no such language as C/C++.
2. Minesweeper was written in either C or C++, therefore by your logic,
we should be able to discuss Minesweeper here.
 
Please also see:
http://www.dietmar-kuehl.de/mirror/c++-faq/how-to-post.html#faq-5.9
fir <profesor.fir@gmail.com>: Dec 19 12:55PM -0800

W dniu wtorek, 19 grudnia 2017 21:03:54 UTC+1 użytkownik red floyd napisał:
> we should be able to discuss Minesweeper here.
 
> Please also see:
> http://www.dietmar-kuehl.de/mirror/c++-faq/how-to-post.html#faq-5.9
 
ofc you should discussing c/c++ programs design here
 
it would be much more interesting and knowledge-giving than discussing language which is for newbs and is boring
 
discuss c/c++ real programmming not language
Vir Campestris <vir.campestris@invalid.invalid>: Dec 19 09:31PM

On 19/12/2017 18:54, fir wrote:
> (and i dont share the view that this or c
> group are only for talking language, if
> so and this is c-language where is c-programming group) (i know its c++ but write c for short, i dislike c++ only like when it covers with c ;c)
 
For C questions comp.lang.c seems a good place to start. I don't follow it.
 
Andy
fir <profesor.fir@gmail.com>: Dec 19 02:06PM -0800

W dniu wtorek, 19 grudnia 2017 22:31:32 UTC+1 użytkownik Vir Campestris napisał:
> > so and this is c-language where is c-programming group) (i know its c++ but write c for short, i dislike c++ only like when it covers with c ;c)
 
> For C questions comp.lang.c seems a good place to start. I don't follow it.
 
> Andy
 
then subscribe, c is great (c is divine)
though they sadly ike here or even more talk about the language instead of real matter
red floyd <dont.bother@its.invalid>: Dec 19 02:18PM -0800

On 12/19/2017 2:06 PM, fir wrote:
 
>> Andy
 
> then subscribe, c is great (c is divine)
> though they sadly ike here or even more talk about the language instead of real matter
 
Because not everything in the entire world is a Windows box...
Christian Gollwitzer <auriocus@gmx.de>: Dec 19 08:38PM +0100

Am 19.12.17 um 16:39 schrieb David Brown:
> in the Windows world, it is more recent (Windows has supported a variant
> of UTF-16 for nearly two decades, but good UTF-8 support and good fonts
> are not as old.
 
This opinion seems very biased. As you say, Windows uses UTF-16
(formerly UCS-2) *internally* for the API to submit a Unicode string to
the display. That doesn't mean that UTF-8 doesn't work there, UTF-8 is
just a transport encoding for Unicode codepoints, and recent ("10 years
old") software can anytime recode it into UTF-16 to call the Windows
API. There is no problem to run Internet Explorer on XP and display a
HTML page encoded in UTF-8.
 
> Remember, Windows XP is the third most popular OS in
> the world!).
 
Very sad, since it is not supported any longer.
 
 
> days of MS-DOS, have it. So someone who is running XP and likes "MS
> sans serif" will have no problem with ö, but will have difficulty with
> directional quotation marks.
 
Quote from Wikipedia: https://en.wikipedia.org/wiki/Microsoft_Sans_Serif
"Version 1.41 (supplied with Windows XP SP2) includes 2257 glyphs (2301
characters, 28 blocks), which extended Unicode ranges to include
Combining Diacritical Marks, Currency Symbols, Cyrillic Supplement,
Geometric Shapes, Greek Extended, IPA Extensions, Number Forms, Spacing
Modifier Letters. New OpenType scripts include Arabic MAR script.
Additional OpenType features includes rlig for Arabic scripts."
 
So, MS Sans Serif actually seems to be a decent Unicode font. Not to
mention "Arial Unicode" which shipped in 2000 with almost everything in
the BMP. I'm inclined to say that the Unicode support used to be much
better in Windows actually than in Linux. I remember a shell tool
"fetchmsttfonts" which downloaded the fonts from Microsoft's servers to
improve the Unicode coverage in Linux.
 
Christian
legalize+jeeves@mail.xmission.com (Richard): Dec 19 08:02PM

[Please do not mail me a copy of your followup]
 
Ralf Goertz <me@myprovider.invalid> spake the secret code
>> simply different.
 
>You say that probably because for your native language there is no
>difference between ASCII and UTF-8.
 
Nope. I say it because most of the time when I encounter UTF-8 laden
email the uses are gratuitous and often the author isn't even aware
that such gratuitous uses of UTF-8 were done "on their behalf." (Yes,
Microsoft, I'm glaring at you.)
 
I am conversationally fluent in French and took several years of
immersion Chinese (mainland, not PRC/traditional; I don't consider
myself fluent by any means, but with a dictionary and enough time I
can translate written text reasonably well). I can certainly appreciate
UTF-8 in contexts where it provides value and I recognize that those
contexts exist aplenty.
 
I certainly would not advocate going back to national character set
extensions of 8-bit ASCII!
 
>to put it differently, with a richer character set in their language) it
>is a huge relief to have an encoding where you don't have to bother
>about code pages and stuff like that.
 
Agreed. One of my first jobs out of college was working at a company
outside Paris and it was an interesting experience reading source code
where all the comments and variable names were in French :).
 
>found myself playing around with those other characters like „…"
>(ellipsis in german style quotation marks) just because I can and it is
>so much nicer. Spoiled by using LaTeX, I guess.
 
Yeah, well to me it looks like a bunch of hex binary characters, so it
just comes out like useless gibberish. And seriously, do we really
need to use a fancy Unicode character when we could just write ... and
be universally clear? I know this is not going to sway you, I'm
simply making the point that while there are Unicode characters for
which there is no adequate representation in ASCII, there are also a
bunch of Unicode characters for which the ASCII representation is just
fine. We're not trying to typeset books on usenet or email, we're
trying to communicate effectively. IMO, most of these kinds of uses
of Unicode are impeding communication rather than enhancing it.
 
But hey, we're all luddites here in the sense that we are using usenet
and not the "forum" on cplusplus.com.
 
>> Just like I find your preference to always use trailing return
>> type :).
 
>With that I agree ;-)
 
My statement was awkwardly worded, but you know I was saying your use
of trailing return type was gratuitous, right? :)
--
"The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline>
The Terminals Wiki <http://terminals-wiki.org>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
legalize+jeeves@mail.xmission.com (Richard): Dec 19 08:06PM

[Please do not mail me a copy of your followup]
 
Ralf Goertz <me@myprovider.invalid> spake the secret code
 
>Can't we assume that in a computer oriented newsgroup like this people
>know how to have UTF-8 displayed correctly after so many years that it
>is around?
 
You can assume it, but it isn't universally true.
 
Just to be clear, I'm not asking for any accommodation of my old tools
:), but UTF-8 still isn't universal. I think this is mostly because
some tools that people like (e.g. me) aren't being actively
maintained.
 
I've investigated the source code for my favorite news reader to see
about updating it, but unfortunately the thing was already a big mess
when the last maintainer stopped updating it themselves. A perfect
example of how open source software gets abandoned because people
allowed the messes to accumulate over time.
 
Kind of like when you watch an episode of "hoarders" and those people
wallowing in all that mess insist they "need" everything and how they
know where everything is. Of course, to any casual outside observer
the thing looks like the contents of a trash dumpster.
--
"The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline>
The Terminals Wiki <http://terminals-wiki.org>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
David Brown <david.brown@hesbynett.no>: Dec 19 09:54PM +0100

On 19/12/17 20:38, Christian Gollwitzer wrote:
> old") software can anytime recode it into UTF-16 to call the Windows
> API. There is no problem to run Internet Explorer on XP and display a
> HTML page encoded in UTF-8.
 
Biased, perhaps, but based on experience. Even though NT had UCS-2
(mostly like UTF-16, but without the support for multi-code encodings)
from the beginning, that was in the kernel and the NTFS filesystem.
Lots of software did not support Unicode of any sort, and the few fonts
with Unicode encoding were very sparse. It got better, of course, with
far better fonts and support by the time of XP, and certainly with Win7
(I skipped Vista entirely) there is no problem with UTF-8 in most
applications. Blame it on slow or lazy app developers, rather than
Windows, if you prefer.
 
>> Remember, Windows XP is the third most popular OS in
>> the world!).
 
> Very sad, since it is not supported any longer.
 
I have never found support or lack thereof for Windows to be of any
significant benefit. But if you mean that the latest versions of some
applications no longer run on XP, then I agree. Generally, however, I
find I can run most programs fine in XP. (I use Win7 for my Windows
desktop, but XP or even W2K when I need a Windows virtual machine. Such
machines are for running particular programs - not for using the latest
and greatest web browsers.)
 
> better in Windows actually than in Linux. I remember a shell tool
> "fetchmsttfonts" which downloaded the fonts from Microsoft's servers to
> improve the Unicode coverage in Linux.
 
Well, experiences vary, I suppose. Perhaps I was unlucky in the fonts I
used or the software I used.
 
"fetchmsttfonts" is (was) mainly to get fonts that are compatible with
common ones from the Windows world - so that your OpenOffice/LibreOffice
documents match up in font metrics, and so that your Windows programs
under Wine work.
 
There was a time when Unicode in Linux was bad too, and fonts were
limited. UTF-8 always worked underneath, because most of Linux and the
filesystems simply ignore the details - UTF-8 strings work the same way
as ASCII strings.
Christian Gollwitzer <auriocus@gmx.de>: Dec 19 10:04PM +0100

Am 19.12.17 um 21:54 schrieb David Brown:
 
> I have never found support or lack thereof for Windows to be of any
> significant benefit.  But if you mean that the latest versions of some
> applications no longer run on XP, then I agree.
 
I meant that Microsoft stopped supporting XP in 2014, i.e. there will be
known unfixable security bugs in XP. For that reason Windows developers
also stop testing their software on XP. There's anyway no good to reason
to stay with XP - unless you have some specialized hardware like, e.g. a
CT scanner or similar stuff.
 
Christian
scott@slp53.sl.home (Scott Lurndal): Dec 19 09:25PM

>>is around?
 
>You can assume it, but it isn't universally true.
 
>Just to be clear, I'm not asking for any accommodation of my old tools
 
I am :-). I've no desire to try to use UTF-8 with the athena widgets
that drive my fast, efficient and lightweight newsreader (xrn),
certainly not to display smart quotation marks.
 
>:), but UTF-8 still isn't universal. I think this is mostly because
>some tools that people like (e.g. me) aren't being actively
>maintained.
 
Hear, Hear!
David Brown <david.brown@hesbynett.no>: Dec 19 10:29PM +0100

On 19/12/17 22:04, Christian Gollwitzer wrote:
> also stop testing their software on XP. There's anyway no good to reason
> to stay with XP - unless you have some specialized hardware like, e.g. a
> CT scanner or similar stuff.
 
When you use Windows, you know it has security bugs. (The same applies
to all systems, of course - but Windows' reputation is, let us say, not
stellar.) When a new version of Windows comes out, there is a flurry of
fixes of the big stuff - gaping holes, or issues that are likely to be
met by many people in practice. But by the time you get past a service
pack or two, these are all done - it is rare that there are security
threats that have a significant risk to normal users who take reasonable
precautions. When you look at the list of security fixes after this
initial period, they are all about local privilege escalations, or holes
in obscure features and services that few people use, or things that are
easily blocked by having a real firewall between your PC and the
internet. Your significant security risks are then from applications,
perhaps especially MS's browsers and other MS software (at least from
the XP era), from user errors (like clicking on random links, opening "I
Love U" emails, and downloading random software), and from broken
"security" software.
 
I simply do not find XP - at least after SP2 when it stabilized - to be
a significant security risk compared to Win7 or later Windows.
 
The reason Windows developers stop supporting XP and testing their code
for XP is that they can use newer features on newer OS's, and testing
takes time and costs money - people with XP are unlikely to pay for that
cost. No Windows application developer thinks "I /could/ support XP and
get a wider customer base. But I want to encourage people to have
better security, so I will disable XP support in my code to force people
to update their OS for their own good".
 
There are lots of reasons to keep running XP. This is perhaps best seen
by looking at the numbers from usage trackers - there are /lots/ of XP
machines in use. And that does not count them all, since many (such as
the CT scanners) are not used for internet browsing. Of course in many
cases, there may not be a good reason for sticking to XP - but a huge
proportion of users really do not see the point in paying lots of money
to "fix" something that is doing a perfectly good job for them.
James Kuyper <jameskuyper@verizon.net>: Dec 19 01:34PM -0500

On 12/18/2017 06:59 PM, Ian Collins wrote:
...
> It's foolish to write of a chunk of a language because it can be abused.
 
"write off"?
Ian Collins <ian-news@hotmail.com>: Dec 20 07:42AM +1300

On 12/20/2017 07:34 AM, James Kuyper wrote:
> ....
>> It's foolish to write of a chunk of a language because it can be abused.
 
> "write off"?
 
Indeed :)
 
--
Ian.
legalize+jeeves@mail.xmission.com (Richard): Dec 19 07:53PM

[Please do not mail me a copy of your followup]
 
Thiago Adams <thiago.adams@gmail.com> spake the secret code
>> >for windows and we don´t have a refactoring tool.
 
>> clang-tidy is pretty much ubiquitous.
 
>But this tool cannot remove old custom macros.
 
Yes, it can. (I've written some of the checks that ship in clang-tidy.)
 
Custom transformations of course require custom code to identify those
transformations. There are some commercial tools out there that have
a custom DSL in which you can write such tranfsormations. However,
clang-tidy doesn't (yet) have such a DSL for specifying
transformations.
 
DMS is a commercial tool for transforming C++ code with a DSL for
specifying the transformations. Here is a lightning talk about it
from CppCon 2017: <https://www.youtube.com/watch?v=86fwuXSz7lQ>
It looks pretty cool from that talk, but I have not experience in
using it. Here is a page from their site explaining code
transformations:
<http://www.semdesigns.com/Products/DMS/ProgramTransformation.html?Home=DMSToolkit>
 
Given that I can't find a price for DMS directly on their prices page,
I'm assuming it's expensive. My guess would be somewhere between $10K
and $50K per seat. Still, that may be cheap compared to modernizing a
legacy code base by hand (and presumably less error prone).
--
"The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline>
The Terminals Wiki <http://terminals-wiki.org>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
scott@slp53.sl.home (Scott Lurndal): Dec 19 09:21PM

>I'm assuming it's expensive. My guess would be somewhere between $10K
>and $50K per seat. Still, that may be cheap compared to modernizing a
>legacy code base by hand (and presumably less error prone).
 
I could see using it for Jovial to C, that makes a lot of sense,
particularly in the context of the B2.
 
I'm not as confident that it would be worth the price for C to C
or C++ to C++, which seems like churn for the sake of churn.
fir <profesor.fir@gmail.com>: Dec 19 01:01PM -0800

have someone here some experience in coding drivers here (esp in windows)
 
and could geve some good story what it is really all about?
 
i would like to get some understanding without reading too much alone
 
 
is my view that coding a driver is like a
coding dll library that would have to implement predefined api (the api that would be used for higher layer dlls) and form the
bottom side it communicated with device?
(but if communicate with device att bottom side, does it do it in some also predefined way? what is that bottom way?)
 
and what else?
James Kuyper <jameskuyper@verizon.net>: Dec 19 02:13PM -0500

On 12/18/2017 07:47 PM, Öö Tiib wrote:
...
> C++ does not have concept of "layout-compatible types" like C has so
> I think the behavior is legal and does not violate standards.
 
The latest version of the C++ standard that I have on my system is
n3797.pdf, 2013-10-13. I uses the term "layout-compatible" twice in
3.9p11, one each in 3.9.2p2 and 7.2p9, twice in 9.2p16 and 9.2p17, and
one last time in 9.2p18.
The term never appears anywhere in the C standard.
James Kuyper <jameskuyper@verizon.net>: Dec 19 02:30PM -0500

On 12/18/2017 07:15 PM, Christopher Pisz wrote:
> {
> assert(sizeof(S1) == sizeof(S2));
> }
 
I'm using n3797.pdf for my citations.
 
"Two standard-layout struct (Clause 9) types are layout-compatible if
they have the same number of non-static data members and corresponding
non-static data members (in declaration order) have layout-compatible
types (3.9)." (9.2p16)
 
Note that "A standard-layout class ... has the same access control
(Clause 11) for all non-static data members". (9p7), a condition met by
both S1 and S2.
 
I expected the standard to assert somewhere that layout-compatible types
have the same size and the same value of offsetof() for each non-static
data member. But if there's any such guarantee, I've been unable to
locate it.
 
About the only constraint I could find on the layout of non-static data
members is that "If two pointers point to different non-static data
members of the same object, or to subobjects of such members,
recursively, the pointer to the later declared member compares greater
provided the two members have the same access control (Clause 11) and
provided their class is not a union." (5.9p3).
Ian Collins <ian-news@hotmail.com>: Dec 20 08:43AM +1300

On 12/20/2017 08:30 AM, James Kuyper wrote:
> recursively, the pointer to the later declared member compares greater
> provided the two members have the same access control (Clause 11) and
> provided their class is not a union." (5.9p3).
 
 
std::is_standard_layout<T> is your friend.
 
--
ian
bartc <bc@freeuk.com>: Dec 19 07:47PM

On 19/12/2017 00:15, Christopher Pisz wrote:
> {
> assert(sizeof(S1) == sizeof(S2));
> }
 
What are the two sizes?
 
--
bartc
"Öö Tiib" <ootiib@hot.ee>: Dec 19 11:54AM -0800

On Tuesday, 19 December 2017 21:13:50 UTC+2, James Kuyper wrote:
> 3.9p11, one each in 3.9.2p2 and 7.2p9, twice in 9.2p16 and 9.2p17, and
> one last time in 9.2p18.
> The term never appears anywhere in the C standard.
 
Yes. I remembered it wrongly. There is layout-compatibility in C++ for
union members with common initial sequence. I meant the sufficiently
similar types of C that were concept of compatible types. I believe
the S1 and S2 of OP were such types until C99.
James Kuyper <jameskuyper@verizon.net>: Dec 19 03:17PM -0500

On 12/19/2017 02:54 PM, Öö Tiib wrote:
> union members with common initial sequence. I meant the sufficiently
> similar types of C that were concept of compatible types. I believe
> the S1 and S2 of OP were such types until C99.
 
All citations in this message are from the C standard, not the C++ one.
 
The only difference between S1 and S2 involves a feature ("public:") not
supported by C99. If you drop that feature, they are compatible types,
but only if declared in separate translation units (6.2.7p1), and
nothing changed in that regard in C99.
 
6.2.7p1 is a peculiar feature of the C standard that deserves some
explanation. You might think that two struct types declared identically
in different translation units would be considered to declare the same
type, but "The presence of a struct-declaration-list in a
struct-or-union-specifier declares a new type, within a translation
unit." The fact that the type's scope is restricted to that translation
unit means that the rule that "Two types have compatible type if their
types are the same." (6.2.7p1) doesn't allow you to say that struct
types defined identically in different translation units are compatible
with each other. Therefore, 6.2.7p1 was added to say that they are.
 
However, the C standard deliberately restricts that rule to types
declared in separate translation units. If you define two struct types
identically in one translation unit, it's assumed that you deliberately
intended them to be distinct types, and that you would therefore want to
get the diagnostic messages you will get if you accidentally mix them up
in contexts where relevant types are required to be compatible.
 
The fact that they are incompatible allows certain optimizations, based
mainly upon the anti-aliasing rules, but because they would be
compatible with identical declarations in a different translation unit,
an implementation is not free to lay them out differently unless it can
be certain that they won't be used for communication between translation
units.
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