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Re: A guide on setting up C/C++ development environment for Emacs


From: Jai Dayal
Subject: Re: A guide on setting up C/C++ development environment for Emacs
Date: Wed, 27 Aug 2014 14:15:17 -0400

Any mention of CEDET always turns into this kind of discussion.


On Wed, Aug 27, 2014 at 2:14 PM, Tu Hoang Do <address@hidden> wrote:

> >
> >  Yes, and it seems to me like a reason to not use C++. Really.
> > It's has so horrible syntax/grammar (compared e.g. to Lisp),
> > so in 2014 there is no complete solution to work with comfort.
> > Seriosly, there is a SLIME, there is a CEDET (which works well only
> > with C), but there is no complete support for C++ around. Only a
> > set of workarounds and disappointments.
> >
>
> Sure, so do I. I took a C job and my C++ is fading away. Probably I only
> use C++ as C with classes and templates. For C++, at least Clang can work
> with it and I've just added a section on how to use company-clang and
> .dir-locals.el to provide project completion:
> http://tuhdo.github.io/c-ide.html#sec-2
>
>
> Yes, I understood about CEDET parsing infrastructure. But the case above
> > is about a CEDET bug, rather than caching
> >
>
> Probably. I haven't encountered the problem. For your first CEDET problem,
> you can use company-semantic and it will give you completion, even without
> anay prefix.
>
> Or I can just use Qt Creator or just abandon the C++ and do my high-level
> >
> abstractions and programming in Lisp, and low-level programming in C.
> >
>
> That works fine. I prefer the later.
>
> On Reddit I had a discussion with another user about IDE like QtCreator vs
> Emacs:
>
> http://www.reddit.com/r/cpp/comments/2efh2c/cc_development_environment_for_emacs/cjz03qr
>
> I can understand the value QtCreator provides, but when I need to work with
> a project with multiple languages (i.e. not only your language source
> files, you also have bash scripts, Makefile, test written in other
> languages, submodules in other languages...) then Emacs will be better in
> general operations. In general, QtCreator provides better C++ support than
> most IDEs and editors, include Eclipse.
>
>
>
> On Wed, Aug 27, 2014 at 11:21 PM, Dmitriy Igrishin <address@hidden>
> wrote:
>
> >
> >
> >
> > 2014-08-27 18:53 GMT+04:00 Tu Hoang Do <address@hidden>:
> >
> > For C, CEDET works really well. For C++, it is a quite incomplete but
> >> usable.  I already showed the smart completion in this screenshot:
> >> http://tuhdo.github.io/static/auto_complete.gif
> >>
> >
> >>
> >> Notice in the screenshot before and after I include linux/printk.h
> CEDET
> >> realizes the change in buffer and adapt immediately. But, as I said, you
> >> need to leave it sometimes for parsing the first time you perform smart
> >> completion from included files. Here is another example with using CEDET
> >> with Boost: http://tuhdo.github.io/static/c-ide/semantic-boost-demo.gif
> >>
> >> CEDET actually understands your source code by trying to parse properly.
> >> It
> >> works mostly with C.
> >>
> > Yes, and it seems to me like a reason to not use C++. Really.
> > It's has so horrible syntax/grammar (compared e.g. to Lisp),
> > so in 2014 there is no complete solution to work with comfort.
> > Seriosly, there is a SLIME, there is a CEDET (which works well only
> > with C), but there is no complete support for C++ around. Only a
> > set of workarounds and disappointments.
> >
> >>
> >
> >>
> >> please, try to M-x semantic-ia-complete-
> >> > symbol-menu
> >> > when you are in method implementation like this:
> >> > void Class::method()
> >> > {
> >> >   // M-x semantic-ia-complete-symbol-menu should show a menu
> >> >   // with all members in the scope. But nothing is shown.
> >> >
> >> }
> >> >
> >>
> >> For this use case, I agree this is a limitation. You need to have a
> prefix
> >> for it to start completion. I think this should be less of a problem
> since
> >> if you have many include files, you have a huge pool of completion
> >> candidates that you have to narrow down anyway.
> >>
> >>
> >> Second example. Please, try to M-x semantic-ia-complete-symbol-menu
> >> > when you are in
> >> > void Class::method()
> >> > {
> >> >   method2(
> >> >   // M-x semantic-ia-complete-symbol-menu after the "(" will
> >> >   // freeze Emacs to do some of stupid thinking.
> >> >   // Terrible, horrible and sad. And nothing more.
> >> > }
> >> >
> >>
> >> Parsing is an intensive task. To make CEDET work well, *you have to
> wait*
> >>
> >> for it to biuld up the database for future use. For an implementation in
> >> Pure Elisp, it is quite fast for reasonable size projects and is cross
> >> platform. Getting Clang to work on Windows is not easy. Also, it is the
> >> limitation of single threaded Emacs. To provides real IDE features like
> in
> >> other IDEs, Emacs needs must be able to do many things at once, like
> >> analyzing and checking. Since Emacs is single threaded, anything heavy
> >> weight blocks it. You have to wait for a few minutes if you only include
> >> like ten header files and your project is not too large. The way it
> works
> >> is like this: for each included file, it parse the that file and if the
> >> included file includes further files it will move deeply into those
> files
> >> and parse until reaching the end.* Subsequent parsing results in less
> >> time *because
> >>
> >> CEDET can make use of previous parsing result. I heard that in the
> future
> >> Emacs will come with cooperative threads, and it makes tasks like
> parsing
> >> and syntax checking can coexist with editing.
> >>
> > Yes, I understood about CEDET parsing infrastructure. But the case above
> > is about a CEDET bug, rather than caching. You may call
> > M-x semantic-ia-complete-symbol-menu after the "(" in the case above many
> > times and Emacs will be freezed many times accordingly.
> >
> >>
> >> After this, I don't want to use CEDET without any sorry.
> >> > Sorry.
> >> >
> >>
> >> Sure. You always have alternatives such as other Clang solutions. But it
> >> won't be complete either. It can complete candidates in system header
> >> files
> >> fine, but if you want to complete for project wise, you have to give it
> >> include paths written in absolute path.
> >>
> >> Or, you can just use GNU Global with Emacs frontend that provides a not
> so
> >> accurate for C++ but practical solution. It's really fast. I can walk
> the
> >> Linux kernel with ease. You can use company-gtags to get a list of all
> >> possible completions in your project.
> >>
> > Or I can just use Qt Creator or just abandon the C++ and do my high-level
> > abstractions and programming in Lisp, and low-level programming in C.
> >
> >>
> >> Thanks.
> >>
> >> On Wed, Aug 27, 2014 at 9:15 PM, Dmitriy Igrishin <address@hidden>
> >> wrote:
> >>
> >> >
> >> >
> >> >
> >> > 2014-08-27 17:18 GMT+04:00 Tu Hoang Do <address@hidden>:
> >> >
> >> > CEDET is not slow. It's reasonably fast given it is implemented in
> Emacs
> >> >> Lisp. It needs time for parsing to build a database, so you see a
> >> message
> >> >> printing this: parsing....<file> in the minibuffer. It needs parsing
> to
> >> >> build up a database for smart completion. After the first time
> parsing,
> >> >> completion happens instantly and you should enable Semanticdb minor
> >> mode to
> >> >> save the parsing results, so CEDET won't have to parse the next time.
> >> CEDET
> >> >> can handle project with the size of Emacs really well. I think even
> >> project
> >> >> with more than a million lines of code. CEDET is the only viable
> >> solution
> >> >> so far I found for real smart completion in Emacs. Other clang based
> >> >> solution is pretty limited: you can only get completion from system
> >> header
> >> >> and current directory, but not for your project. You have to add the
> >> >> include paths to tell Clang where your project include paths are, and
> >> you
> >> >> have to specify with absolute paths. It's really tedious.
> >> >>
> >> > No, it does not real smart. For example, please, try to
> >> > M-x semantic-ia-complete-symbol-menu
> >> > when you are in method implementation like this:
> >> > void Class::method()
> >> > {
> >> >   // M-x semantic-ia-complete-symbol-menu should show a menu
> >> >   // with all members in the scope. But nothing is shown.
> >> > }
> >> > Second example. Please, try to M-x semantic-ia-complete-symbol-menu
> >> > when you are in
> >> > void Class::method()
> >> > {
> >> >   method2(
> >> >   // M-x semantic-ia-complete-symbol-menu after the "(" will
> >> >   // freeze Emacs to do some of stupid thinking.
> >> >   // Terrible, horrible and sad. And nothing more.
> >> > }
> >> >
> >> > After this, I don't want to use CEDET without any sorry.
> >> > Sorry.
> >> >
> >> > --
> >> > // Dmitriy.
> >> >
> >> >
> >>
> >
> >
> >
> > --
> > // Dmitriy.
> >
> >
>


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