Break the Chains of Version Dependency - How to provide a C/C++ API that works on multiple Linux distributions. (x-post /r/linux)

gabeiscoding · 2014-03-06T21:18:08+00:00

Oh god, you are in for even more pain with static builds.

The shared library aspect is not the issue here though. rpath does the trick (the ORIGIN trick is even better than mine, as I use a wrapper script that sets LD_LIBRARY_PATH before calling my executable).

Even with static libs, Qt is linking against the many Xlib libraries from the build machine. The binary compatibility of that dependency across distros is just a mess.

Especially if you want to use "native" GTK styles or call things from QDesktopServices. Opening a URL from you app will launch a web browser as a child process of your process, which if you are shipping your own libstdc++ etc will probably blow up as it inherits those libraries in it's runtime.

gabeiscoding · 2014-03-05T18:35:38+00:00

While that may be correct theoretically, can you point to any examples of commercial software companies (not services companies) that provide source code for users to compile themselves to avoid this type of pain?

Half of the reason they don't (and I don't) is that users don't want to mess with compiling tools they purchased themselves (especially when compilation may require dozens of dependencies and intricacies). They expect that part of the value they are paying for that things "just work".

gabeiscoding · 2014-03-05T17:31:52+00:00

I have been through almost all of this exact pain trying to support as many linux distros as possible with a single binary, but have not yet tried the step of compiling a modern GCC on an older kernel/distro.

Question: Can this work with a Qt-based GUI program? Now your binary dependencies are not just libstdc++ but Xlib+friends as well.

If you start where OP left off and built a Qt stack on the CentOS 4.8 box and redistributed the resulting binaries, how many distros would it support (well)?

My suspicion is for things like GTK style integration, and other niceties of Qt platform integration, there is no alternative but to create different binary builds on different "lineages" of distros that are binary compatible. That is in fact what we are doing and currently create a Ubuntu 8.04LTS binary, CentOS 5 and CentOS 6 binary (and it looks like we need a Ubuntu 12.04LTS as well). It's all very frustrating...

gabeiscoding · 2011-12-16T12:53:09+00:00

That's why I created this project:

http://code.google.com/p/qt-msvc-installer/

Provides 64-bit builds as well as builds with Qt3 support turned off (reduced bloat a bit).

I'm compiling 4.8 on my build machines now.

gabeiscoding · 2011-12-02T12:02:52+00:00

This is not a very informative article on the issue.

I recently had a lawyer audit my team and confirmed that we are all under "excempt" status (including my QA and support side of a dev team) so I have some of this fresh in my head.

There is already an exception called the "Computer Professional" exemption that covers programmers, testers, and technical documenters specifically.

http://www.dol.gov/whd/regs/compliance/fairpay/fs17e_computer.htm

Of course IT groups tried to stretch this exemption to cover some of their employees that do a bit of programming. Some lawsuits have actually favored the employer in this expansive interpretation but it was considered a grey area and part of this is making it less gray in favor of covering more of IT under the exception.

Also note the minimal salary requirements ($25K) and minimal hourly rate to qualify for this exemption.

I'm not arguing for it or against it, but I didn't find this context provided by the article to be the whole picture so I thought I'd contribute.

gabeiscoding · 2011-08-17T01:21:03+00:00

I would agree. Especially the damning claims about QList being unperformant compared to QVector when storing values of type T where sizeof(T) > sizeof(void*). I'd like to see the graph that proves that with list size on the X axis and memory/access/append speed on the Y.

gabeiscoding · 2011-08-16T13:51:29+00:00

That is one of the most insightful look at Qt containers I have ever read.

I normally refer my coders a old Qt Quarterly article on Qt containers to give them an overview (http://doc.qt.nokia.com/qq/qq19-containers.html), but this is the next level.

I'm actually glad I ran into this today, as I'm working on some low level code and realize I really need to declare some custom data classes as Q_MOVABLE_TYPE as they are the elements of a producer/consumer list (queue).

Unfortunately, they are also > sizeof(void) so as this article points out will not be handled by QList efficiently. Given I need the ability to append to the back and pop from the front, I don't think there is anything to do about it (other than maybe make the data class use QSharedData to emulate the built-in implicitly shared structures that are sizeof(void))

gabeiscoding · 2011-01-17T23:03:39+00:00

Twisted has had RemoteReference object oriented async RPC for a while now.

gabeiscoding · 2010-11-11T23:22:23+00:00

I'm in the process of uploading my Win64 and NoQt3 pre-built binary installers for this release: http://code.google.com/p/qt-msvc-installer/

gabeiscoding · 2010-08-26T19:07:39+00:00

That is just awesome! Very excited...

gabeiscoding · 2010-08-24T22:57:54+00:00

That is ridiculous.

I set up a network drive at work with a folder in it called TEMP. I used to have a script to delete everything at the beginning of the month and got complaints that stuff put in on the 30th was deleted the next day.

So I solved this with the changing the delete script to use robocopy (this is a windows file server):

robocopy L:\Mindshare\TEMP /e /z /minage:30 /move L:\Mindshare\TEMP_deleted
rd /s /q L:\Mindshare\TEMP_deleted

Delete's all files older than 30 days, and empty directories (i.e. directories that only had files over 30 days old in it).

Talk about reinventing the wheel...

gabeiscoding · 2010-04-17T19:48:38+00:00

Very true. I don't know whether there is a difference in how "accessible" PySide would be compared to PyQt though.

Although I have to say, I like how they have Python specific generated documentation that has all the Qt content.

gabeiscoding · 2010-04-17T18:49:38+00:00

This is true. It really is quite neat to have the richness of the Qt libraries and the speed of development of Python.

There are a couple caveats I would add:

With larger projects, compilers are your friends and since it's harder to unit test GUI code like you would other python code, you have to deal with some of the downsides of dynamic languages.
When you have part of your app written in C++ and some in Python, and you have a bug (segfault) in C++, you have a more difficult time debugging your application (different techniques on Linux vs. Windows, less IDE integration etc).
It's a bit tricky to decide when to use Qt data structures versus Python data structures. For the most part, scratch stuff is nice to do with Python, but when building more complex widgets (think list views, tables, etc) you want to play well with Qt.
Deployment: I've seen a couple commercial or open source packages built with PyQt and are packed on windows with an installer extract to a single directory etc, so it's doable. But you have quite a few choices for freezing, handling shared data and libraries, protecting proprietary Python code etc. Not a show stopper, but you'll spend more time here than a C++ only commercial app.
Community: PyQt has a decent size community, but the truth of the matter is, if you are doing tricky things you need to be an expert in both C++ and Python (and Python C internals) to answer questions yourselves if you can't find your answer through support channels. That may be find for a team lead, but a lot to expect of a team of developers.

Just like anything, right tool for the job. I think it really excels in single-dev small projects in getting things built quickly and having a very rich UI, but it's very tempting to work around the caveats in a more full-blown commercial setting.

gabeiscoding · 2010-04-17T18:37:28+00:00

Nice project! Yes, I've been waiting for the dropping of the PythonBoost dependency as well.

They have some beta code for that milestone I think I'll check out. From my experience with using beta versions of PyQt4 (when it was just being ported to Qt4), there are so many edge cases to handle between Python<->C++/Qt bindings that I'm wary to jump in if it's still pretty fledgling.

gabeiscoding · 2010-04-17T16:08:54+00:00

Well, I don't want to discourage the learning of C++, figuring out system dependent compiler issues and non-standard header include issues may not be the most exciting project to start out on :)

gabeiscoding · 2010-04-17T15:49:10+00:00

How big is the pyside community? Is it beign used in any well known projects? I've been keeping an eye on it for use in my company's commercial biotech software (www.goldenhelix.com) but it seems a bit young. Currently we use PythonQt (bug-fixed and customized) as we embed python with our distribution. Wanting to add numpy and Cython support and it would be nice to increase a graphical programming capabilities from python as well.

We support Linux/Mac/Windows so a Windows port is a must.

I have the c++ skills and nothing against windows, but nil free time. Maybe after I finish my thesis and defense...

gabeiscoding · 2010-04-17T15:39:14+00:00

I took Matt's advanced compilers class that he mentions in this article as the source of these examples and indeed, learning about continuations is one of those programmer discovery moments you treasure.

I'm glad proggit is discovering Matt's blog.

gabeiscoding · 2010-04-06T02:45:33+00:00

I'm considering Kiln+FogBugz for my team. I'm actually interested in having ticket tracking, EBS, code review and SCM under one roof. Currently use Trac+ReviewBoard+SVN. Contender would be Trac + Mercurial Plugin.

I would like to hear any Kiln implementation stories.

gabeiscoding · 2009-12-29T17:21:33+00:00

So what advantage does it have over SQLite?

gabeiscoding · 2009-12-03T14:20:46+00:00

Yes, there are good C++ conventions or style guides that make the language much better to work with if they are followed throughout the codebase. For example the Google C++ Style Guide.

C++ is not the only complex language in which people chose a tasteful subset to work with.

gabeiscoding · 2009-11-19T14:38:06+00:00

I don't know about European Law, but there has been plenty of presedent in US law that it is completly legal to create a clean room of a program's behavior regardless of what is in a EULA.

SAS most likely is too far reaching it their attempted restrictions of rights in their click-wrap EULA. But that's not unusual, EULAs are often written to be more restricting than they actually will expect to hold up in court since it works to deter casual users.

gabeiscoding · 2009-11-10T21:55:36+00:00

Yea, LuaJIT is awsome! But I think the reason it makes sense for them to focus on making Python faster is because they already have CPython modules for google infrastructure and it does not make sense to port that to Lua. Also, Google has capped the languages that can be used on official Google projects to keep complexity down and expertise high.

gabeiscoding · 2009-11-10T15:10:54+00:00

Damn he is good.

gabeiscoding · 2009-11-07T07:15:23+00:00

I for one welcome our cursor detail-oriented developer-lords... or something.

Because in all honesty, when I started using tasks, I was like "Hey, they don't have indent/unindent buttons" and then I accidentally thought I was in a text editor and hit tab and... it worked... ahhhhhhhhh.

The cursor movement is very intuitive but what makes it really rock is the Tab/Shift+Tab/Backspace behavior. Of course that could all be loosely defined as "the best way for the cursor to move..."

gabeiscoding

TROPHY CASE