Re: Voting for std.experimental.checkedint

[Walter Bright via Digitalmars-d]

On 2/26/2017 1:15 PM, Andrei Alexandrescu wrote:

Indeed, the routines in core.checkedint are everything needed (in addition to
some inline code for comparisons) if the purpose is to check operations
individually.


The purpose of core.checkedint is to provide the smallest possible building 
block for doing checked integers. This is to encapsulate it so it:


1. can be made portable

2. can be recognized by the compiler with the potential for using the knowledge 
of the semantics of it to generate /better/faster/reliable/more correct/ code


3. is a clue to the reader of the code what the point of the odd looking 
expressions is


As John Regehr pointed out in a series of articles,

  http://blog.regehr.org/archives/1139

most people do ad-hoc checking which turns out to be very fragile in the face of 
compiler optimizations and handling of undefined behavior.

Re: Voting for std.experimental.checkedint

[Andrei Alexandrescu via Digitalmars-d]

On 2/26/17 4:53 AM, Seb wrote:

On Sunday, 26 February 2017 at 09:41:46 UTC, rumbu wrote:

On Saturday, 25 February 2017 at 15:21:10 UTC, Andrei Alexandrescu wrote:

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- Andrei


This was not about coding skills, was about usability. The module
contains too many options and failure scenarios instead of a simple
default behavior.

Considering that in most languages with integrated overflow checking,
the default behavior is throwing some kind of exception (Ada, C#,
Pascal, Rust, Swift)


If you want a module with a lot less features, the low-level
core.checkedint might be interesting for you:

http://dlang.org/phobos/core_checkedint.html


Thanks for making this point. I agree with the sentiment "you mean I 
need a 1 KLOC library just to check a handful of operations?" This 
paradox is very interesting and worth looking into.


(BTW the number of lines as dscanner --sloc counts is 1261.)

Indeed, the routines in core.checkedint are everything needed (in 
addition to some inline code for comparisons) if the purpose is to check 
operations individually. However, if the intent is to check for errors 
systematically for certain values or program fragments, that doesn't 
scale; before long, the code becomes a bloatfest. Not to mention the 
difficulty in making sure that all operations of interest have been, in 
fact, covered.


So the next logical step is to attempt encapsulation of these checks in 
a type. Here is where one way or another the code bulk must increase, 
and the key question here is how much ability to customize you get per 
unit of code increase.


One issue with checked integers in general, and as a standard (i.e. 
highly reusable) library in particular, is that they are quite project 
specific: what to do upon violation, and which operations to verify and 
which to let run at full speed. As soon as a library does something even 
slightly different from what's necessary, the usability and efficiency 
margins are so narrow, you need to throw the library away and write your 
own. This is very opposite from, say, writing a sorting algorithm 
wherein the API design is very narrow and the difficulty is in the 
algorithm itself. So if you want to write a highly reusable checkedint 
library, you must put ability to customize front, left, and center.


I've started work on an article on DbI, and did a little research on 
other libraries. I found these:


* Mozilla's CheckedInt: 
https://hg.mozilla.org/mozilla-central/file/tip/mfbt/CheckedInt.h, 
clocking at only 791 LoC (no docs and unittests). Though compact and 
ingenious, it makes two design decisions that I think are problematic: 
(a) it stores a "valid" bit (which costs an actual word) together with 
the integral value 
(https://hg.mozilla.org/mozilla-central/file/tip/mfbt/CheckedInt.h#l503), 
which leads to an inefficient layout and also puts all enforcement onus 
on the user; and (b) it separates overflow checks from the actual 
operations, which leads to bulky and inefficient overflow checks (see 
e.g. 
https://hg.mozilla.org/mozilla-central/file/tip/mfbt/CheckedInt.h#l256 
for addition).


* https://safeint.codeplex.com by Microsoft - a behemoth of a library 
clocking at 7055 LoC including comments. Speed is an explicit goal. It 
makes a number of design decisions that might not work for everyone, for 
example:


- accepts (somewhat obliquely) implicit conversion back to the 
representation type, which is kind of defeating the purpose


- taking the address decays to a pointer to unchecked integral (what?)

- has a rigid error policy (either assert or throw)

- the checks and the error handling policies are awkwardly controlled 
via command line instead of template parameters


- binary operators don't work against two SafeInts

- signed/unsigned comparisons are not checked (this is a consequence of 
the implicit decay)


* https://github.com/robertramey/safe_numerics, meant as an addition to 
Boost. That's also a large lbrary (4969 lines with light comments, going 
up to over 10K lines with unittests, and requiring 6 other Boost 
libraries: MPL, Integer, Config, Concept Checking, Tribool, and 
Enable_if). The author also wrote a recent article (Overload Feb 2017) 
that describes the library: 
http://www.rrsd.com/software_development/safe_numerics/Overload137.pdf. 
The article does a great job at motivating such libraries. The facility 
allows good error policy customization, and allows to some extent 
customizing the checks being done (only for promotions). It also has a 
mode that is at least theoretically interesting - it expands the result 
of operations whenever possible to preserve correctness, and refuses to 
compile code that might overflow. I speculate that that feature is of 
very limited use; in just a couple of steps everything goes to 64 bits, 
and we're done. The implementation has the 

Re: Voting for std.experimental.checkedint

[Seb via Digitalmars-d]

On Sunday, 26 February 2017 at 10:34:07 UTC, Patrick Schluter 
wrote:

On Sunday, 26 February 2017 at 09:53:42 UTC, Seb wrote:

On Sunday, 26 February 2017 at 09:41:46 UTC, rumbu wrote:

[...]


If you want a module with a lot less features, the low-level 
core.checkedint might be interesting for you:


http://dlang.org/phobos/core_checkedint.html


[...]



It is now: 
http://dlang.org/phobos-prerelease/std_experimental_checkedint.html


If this is still unclear, please submit a PR to improve the 
docs! ;-)


The runnable examples fail at compilation with
/d947/f268.d(1): Error: module checkedint is in file 
'std/experimental/checkedint.d' which cannot be read


Yes that's expected as DPaste doesn't support dmd-nightly builds 
:/
There's not much I can update this - the maintainer of DPaste 
hasn't been very active recently.

So if you want to do sth. about it, there are two ways:

1) Ping him friendly -> https://github.com/nazriel
2) Write your DPaste replacement (could be based on the 
dlang-tour [1])


[1] https://github.com/stonemaster/dlang-tour/issues/501

Re: Voting for std.experimental.checkedint

[Patrick Schluter via Digitalmars-d]

On Sunday, 26 February 2017 at 09:53:42 UTC, Seb wrote:

On Sunday, 26 February 2017 at 09:41:46 UTC, rumbu wrote:

[...]


If you want a module with a lot less features, the low-level 
core.checkedint might be interesting for you:


http://dlang.org/phobos/core_checkedint.html


[...]



It is now: 
http://dlang.org/phobos-prerelease/std_experimental_checkedint.html


If this is still unclear, please submit a PR to improve the 
docs! ;-)


The runnable examples fail at compilation with
/d947/f268.d(1): Error: module checkedint is in file 
'std/experimental/checkedint.d' which cannot be read

Re: Voting for std.experimental.checkedint

[Seb via Digitalmars-d]

On Sunday, 26 February 2017 at 09:41:46 UTC, rumbu wrote:
On Saturday, 25 February 2017 at 15:21:10 UTC, Andrei 
Alexandrescu wrote:

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- 
Andrei


This was not about coding skills, was about usability. The 
module contains too many options and failure scenarios instead 
of a simple default behavior.


Considering that in most languages with integrated overflow 
checking, the default behavior is throwing some kind of 
exception (Ada, C#, Pascal, Rust, Swift)


If you want a module with a lot less features, the low-level 
core.checkedint might be interesting for you:


http://dlang.org/phobos/core_checkedint.html

this one must be at least [be] highlighted at the top of the 
documentation.



It is now: 
http://dlang.org/phobos-prerelease/std_experimental_checkedint.html


If this is still unclear, please submit a PR to improve the docs! 
;-)

Re: Voting for std.experimental.checkedint

[rumbu via Digitalmars-d]

On Saturday, 25 February 2017 at 15:21:10 UTC, Andrei 
Alexandrescu wrote:

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- Andrei


This was not about coding skills, was about usability. The module 
contains too many options and failure scenarios instead of a 
simple default behavior.


Considering that in most languages with integrated overflow 
checking, the default behavior is throwing some kind of exception 
(Ada, C#, Pascal, Rust, Swift), this one must be at least 
highlighted at the top of the documentation.

Re: Voting for std.experimental.checkedint

[Andrei Alexandrescu via Digitalmars-d]

On 2/25/17 11:00 AM, Vladimir Panteleev wrote:

On Saturday, 25 February 2017 at 15:21:10 UTC, Andrei Alexandrescu wrote:

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- Andrei


Perhaps a simpler example for the most basic use case could be added
near the top. In the heat of solving a problem, encountering two pages
of theory and explanation for something the usage of which should be
simple might be discouraging.

Basically, something like:

writeln((checked(5) + 7).get); // 12
writeln((checked(10) * 1000 * 1000 * 1000).get); // Overflow on binary
operator


OK, let's do this:

https://github.com/dlang/phobos/pull/5192
https://github.com/dlang/phobos/pull/5195


Thanks,

Andrei

Re: Voting for std.experimental.checkedint

[Vladimir Panteleev via Digitalmars-d]

On Saturday, 25 February 2017 at 15:21:10 UTC, Andrei 
Alexandrescu wrote:

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- Andrei


Perhaps a simpler example for the most basic use case could be 
added near the top. In the heat of solving a problem, 
encountering two pages of theory and explanation for something 
the usage of which should be simple might be discouraging.


Basically, something like:

writeln((checked(5) + 7).get); // 12
writeln((checked(10) * 1000 * 1000 * 1000).get); // Overflow on 
binary operator

Re: Voting for std.experimental.checkedint

[Andrei Alexandrescu via Digitalmars-d]

On 02/25/2017 10:17 AM, rumbu wrote:

A lot of bloat code for something extremely basic.


If you can do it with less code, I'm all ears. Thanks! -- Andrei

Re: Voting for std.experimental.checkedint

[rumbu via Digitalmars-d]

On Friday, 24 February 2017 at 20:37:28 UTC, Dmitry Olshansky 
wrote:

On 2/24/17 4:20 PM, Robert burner Schadek wrote:

checkedint got voted in. With 2 Yes and 2 yes with remarks.



Remarkably unpopular vote we have here.
If I read it right it implies that
nobody cares for checked integers.



A lot of bloat code for something extremely basic.

Newbie asks: How do I check for integer overflow in D?
Response: 
http://dtest.thecybershadow.net/artifact/website-f99d0fe6d09e288faf22f3eb515fc56e3c892179-48800882159648c96641690c7485b586/web/phobos-prerelease/std_experimental_checkedint.html


* newbie runs scared.

My 2 cents.

Re: Voting for std.experimental.checkedint

[Ola Fosheim Grostad via Digitalmars-d]

On Friday, 24 February 2017 at 20:37:28 UTC, Dmitry Olshansky 
wrote:

On 2/24/17 4:20 PM, Robert burner Schadek wrote:

checkedint got voted in. With 2 Yes and 2 yes with remarks.



Remarkably unpopular vote we have here.
If I read it right it implies that
nobody cares for checked integers.


It is more useful as a compiler switch, a type won't help when 
you call into third party libraries.

Re: Voting for std.experimental.checkedint

[Jack Stouffer via Digitalmars-d]

On Friday, 24 February 2017 at 20:37:28 UTC, Dmitry Olshansky 
wrote:
If I read it right it implies that nobody cares for checked 
integers.


I guess you can say I don't personally care about them because I 
have no personal use case for them. But, as I said in my remarks, 
I understand why we should have them. Time will tell from users 
if this solution is workable.

Re: Voting for std.experimental.checkedint

[Dmitry Olshansky via Digitalmars-d]

On 2/24/17 4:20 PM, Robert burner Schadek wrote:

checkedint got voted in. With 2 Yes and 2 yes with remarks.



Remarkably unpopular vote we have here.
If I read it right it implies that
nobody cares for checked integers.


I will set the autotester to merge.

Thank you @andralex for the hard work.


---
Dmitry Olshansky

Re: Voting for std.experimental.checkedint

[Robert burner Schadek via Digitalmars-d]

checkedint got voted in. With 2 Yes and 2 yes with remarks.

I will set the autotester to merge.

Thank you @andralex for the hard work.

Re: Voting for std.experimental.checkedint

[Meta via Digitalmars-d]

On Friday, 13 January 2017 at 12:39:38 UTC, Robert burner Schadek 
wrote:
This is the voting thread to decide if the proposed addition to 
Phobos, std.experimental.checkedint, should be accepted.


To vote, please respond to this post. You have three options:

* Yes
* Yes with a single condition
* No

If you vote "yes" you can still mention something you'd like 
improved, but please be explicit if that problem is a non 
starter for you and you are choosing option two. If you vote 
no, please state why, though you aren't required to.


Some things to consider when making a vote:

* Is this functionality needed in Phobos?
* The API is practically permanent once the module is accepted. 
Some minor changes can be made, but a full redesign is no 
longer an option.


The voting will end 2017-01-31

The PR can be found here:
https://github.com/dlang/phobos/pull/4613

The dub package can be found here:
http://code.dlang.org/packages/checkedint_andralex

The review thread can be found here:
http://forum.dlang.org/post/mnounbaobgphbmanf...@forum.dlang.org


Yes, with the comment that this would probably be better as a Dub 
package, at least for the time being. If std.experimental didn't 
exist I would say no outright.

Re: Voting for std.experimental.checkedint

[Guillaume Piolat via Digitalmars-d]

On Tuesday, 17 January 2017 at 11:53:16 UTC, Atila Neves wrote:


Same here.

Atila


No interest either. Have zilch problems with integers.

Re: Voting for std.experimental.checkedint

[deadalnix via Digitalmars-d]

Alright some feedback.

It is rather disappointing that Warn and Abort only write to 
stderr. Being able to specify the sink would be great. i may want 
to log the issue or something.


There is option to throw on error.

Checked!(Checked!(int, ProperCompare), WithNaN) is rather 
inelegent. Why not Checked!(int, ProperCompare, WithNaN) ?


get() should not be inout. It returns a value type. const is fine.

Otherwise, the overall design looks pretty solid. Congrats to you 
guys. Idealy, I'd like to see these things polished, but I'm 
rather pleased to see where this is going.


I'd say yes, modulo the above.

Re: Voting for std.experimental.checkedint

[Chris Wright via Digitalmars-d]

On Fri, 13 Jan 2017 12:39:38 +, Robert burner Schadek wrote:

> This is the voting thread to decide if the proposed addition to Phobos,
> std.experimental.checkedint, should be accepted.
> 
> To vote, please respond to this post. You have three options:
> 
> * Yes * Yes with a single condition * No

Yes.

Most of the time in my code, integer overflow is a bug. I want to defend 
myself against bugs. My new code will use checkedint by default (with 
some convenience aliases, and with regular integers as an option in the 
public interface).

There are some minor documentation changes I would like; I have submitted 
a PR.

Re: Voting for std.experimental.checkedint

[Atila Neves via Digitalmars-d]

On Monday, 16 January 2017 at 19:51:38 UTC, Jonathan M Davis 
wrote:
On Saturday, January 14, 2017 20:54:11 Jack Stouffer via 
Digitalmars-d wrote:
On Friday, 13 January 2017 at 12:39:38 UTC, Robert burner 
Schadek


wrote:
> ...

Overall, the code looks good and the design looks solid. 
However, I have no personal use for such a module, so I can't 
really comment on it's design with any authority.


Abstain.


That's pretty much the boat I'm in, though I've never looked at 
it in depth. It's one of those things that a few folks seem to 
think is vital, but I have zero use for it. It's trying to 
solve a problem that I simply don't have.


- Jonathan M Davis


Same here.

Atila

Re: Voting for std.experimental.checkedint

[Bastiaan Veelo via Digitalmars-d]

On Friday, 13 January 2017 at 13:25:10 UTC, Robert burner Schadek 
wrote:

On Friday, 13 January 2017 at 12:49:53 UTC, deadalnix wrote:

Is the doc available somewhere in a readable form ?


CyberShadow/DAutoTest build the docs, you can find the link at 
the end of the PR under checks


Readers trying to find that link on their phone should switch to 
the desktop version (link at the very bottom of the page.)


However volatile, at the moment the docs are here: 
http://dtest.thecybershadow.net/artifact/website-f99d0fe6d09e288faf22f3eb515fc56e3c892179-48800882159648c96641690c7485b586/web/phobos-prerelease/std_experimental_checkedint.html


Bastiaan.

Re: Voting for std.experimental.checkedint

[Thorsten Sommer via Digitalmars-d]

Yes

Re: Voting for std.experimental.checkedint

[Jonathan M Davis via Digitalmars-d]

On Saturday, January 14, 2017 20:54:11 Jack Stouffer via Digitalmars-d 
wrote:
> On Friday, 13 January 2017 at 12:39:38 UTC, Robert burner Schadek
>
> wrote:
> > ...
>
> Overall, the code looks good and the design looks solid. However,
> I have no personal use for such a module, so I can't really
> comment on it's design with any authority.
>
> Abstain.

That's pretty much the boat I'm in, though I've never looked at it in depth.
It's one of those things that a few folks seem to think is vital, but I have
zero use for it. It's trying to solve a problem that I simply don't have.

- Jonathan M Davis

Re: Voting for std.experimental.checkedint

[Jack Stouffer via Digitalmars-d]

On Friday, 13 January 2017 at 12:39:38 UTC, Robert burner Schadek 
wrote:

...


Overall, the code looks good and the design looks solid. However, 
I have no personal use for such a module, so I can't really 
comment on it's design with any authority.


Abstain.

Re: Voting for std.experimental.checkedint

[Robert burner Schadek via Digitalmars-d]

On Friday, 13 January 2017 at 12:49:53 UTC, deadalnix wrote:

Is the doc available somewhere in a readable form ?


CyberShadow/DAutoTest build the docs, you can find the link at 
the end of the PR under checks

Re: Voting for std.experimental.checkedint

[deadalnix via Digitalmars-d]

Is the doc available somewhere in a readable form ?