[vtkusers] " " vs < > for includes

[Julien Lamy]

David Doria a écrit :
> I noticed that most of the includes are done like this:
> #include "vtkPolyData.h"
> 
> Don't the quotes mean "look in the current directory", where
> #include <vtkPolyData.h>
> 
> means "look on the PATH"?

According to the C standard, the <something.h> form searches in a list
of implementation-defined places. The "something.h" searches in
/another/ list of implementation-defined places, and if the file is not
found, proceeds as for the <something.h> form (cf.
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf, page 161).

The specific behavior for gcc is there :
http://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html

> If this is correct, shouldn't they all use <> since we want to find
> headers in all of the subdirectories (VTK/Graphics, VTK/Filtering,
> etc), which I assume have been put on a header_path type variable by
> cmake?
> 
> It clearly works the way it is and I'm sure it is "correct" since the
> whole project does it like this, I was just curious.

Since the places searched by the "something.h" form is a superset of the
<something.h> form, the "correct" way of doing is, in my opinion, just a
matter of conventions. What I've seen most of the time is to use the
quote form for files local to the project and the bracket form for
external files.