[vtk-developers] Python Wrapping fails in master build.

Andrew Maclean andrew.amaclean at gmail.com
Mon Sep 24 18:18:03 EDT 2018


Awesome, I'll try it out now and over the next few days and let you know
how it goes.

Andrew

On Tue, Sep 25, 2018 at 6:41 AM David Gobbi <david.gobbi at gmail.com> wrote:

> Hi Andrew,
>
> I've merged a patch that has a minuscule chance of fixing your wrapper
> issue:
> https://gitlab.kitware.com/vtk/vtk/merge_requests/4697
> This is a patch to vtkWrapPython that closes the output *Python.cxx file
> prior to exit (of course, the Windows loader should close all open files on
> exit automatically, which isn't an excuse for the missing "fclose()" in the
> code, but it does suggest that this patch will have no net effect).  The
> patch also fixes an instance where an error could occur without an error
> message being printed.
>
>
> With regards to incremental builds, there are deficiencies in the
> dependency tracking for wrappers, and even though I don't think they are
> related to the build problems that you are seeing, they are worth
> mentioning:
>
> When vtkWrapPython reads a header for wrapping, it must also handle all
> the #include statements so that it can look for macros and definitions much
> like a C++ compiler would.  In other words, each file is #included should
> be a dependency, but most build systems can only handle such dependencies
> for rules that call the C++ compiler itself, and not for custom commands
> like vtkWrapPython.
>
> There actually are two backend-specific ways to handle such dependencies
> in cmake:
> (1) For the "Makefile" generator, cmake can generate the dependencies on
> the first build but the dependency list becomes out-of-date on subsequent
> builds.
> (2) For the "Ninja" generator, and only for very recent versions of cmake,
> it would be possible to add a customized dependency-generation rule, but I
> haven't looked into it in much detail (it would be a lot of work to
> implement, and wouldn't work on any other backends).
>
> However, the kinds of incremental build changes that cause wrapper builds
> to fail are rare, and the build errors that you saw are not indicative of a
> dependency problem.
>
>  - David
>
>

-- 
___________________________________________
Andrew J. P. Maclean

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