Re: [O] Details of compling and running C++ code from Org-mode?

[Eric Schulte]

Hi Michael,

Michael Hannon <address@hidden> writes:

> Greetings.  I'm curious about the process of executing a program that is
> compiled from a source block in Org-mode.
>
> Some background: I was playing with some C++ code (a slight generalization of
> some code I found in a book).  I wanted to use the "assign" method to
> initialize a vector, as:
>
>     vector<int> testVec(5, 0);
>     testVec.assign({2, 4, 6, 8, 10});
>
> It turns out that to do this one has to tell g++ (in my case) to use the
> latest version of the C++ standard.  I discovered that I could do this via:
>
>     (setq org-babel-C++-compiler "g++ -std=c++0x")
>

You could also use the :flags header argument (:flags "-std=c++0x") to
pass this flag to g++.

>
> This got me to wondering if there were any similar hooks that relate to
> running the program once it's compiled.  I looked through the list of
> org-babel* variables, but didn't find anything obvious.
>
> So what does happen when I hit C-c C-c in, say, a cpp source-code block?  The
> contents of the file are evidently written to a temporary file, after which
> the command specified by org-babel-C++-compiler is run on that file.  The
> results of the compilation are stuck some place -- another temporary file, I
> suppose.  Then the second, executable file is run and the results
> collected.

Thanks for asking this question, and sorry it took so long to respond.
I've placed an annotated copy of the relevant code up at [1] which
should explain the evaluation process for c/c++ code.  In many cases
browsing the relevant org-babel-execute:* function for your language is
the best way to discover what flags are available.

> 
> What command runs the file?

The file itself is called directly.

>   Is there any control from Org-mode over this second stage of the
> process?

Yes, the :cmdline header argument may be used to pass values to the
executing file.

Best -- Eric

>
> Thanks,
>
> -- Mike
>


Footnotes: 
[1]  http://cs.unm.edu/~eschulte/data/babel-c-execution.html
     http://cs.unm.edu/~eschulte/data/babel-c-execution.org

-- 
Eric Schulte
http://cs.unm.edu/~eschulte/