Re: [boost] Boost.Filesystem for Universal Windows (windows-api=store)

Subject: Re: [boost] Boost.Filesystem for Universal Windows (windows-api=store)
From: Mikael Olenfalk (mikael.olenfalk_at_[hidden])
Date: 2015-10-06 08:19:07

On Tue, Oct 6, 2015 at 12:40 PM, Beman Dawes <bdawes_at_[hidden]> wrote:

> On Fri, Oct 2, 2015 at 9:27 AM, Mikael Olenfalk <mikael.olenfalk_at_[hidden]
> >
> wrote:
>
> >
> > https://github.com/boostorg/filesystem/pull/18
>
>
> Ouch! That is a large change. The line count is  +231 −24.
>
>
I might have been able to keep the line-count lower I think but I did some
cleanup (in separate commits) at the same time to make the review easier
and the resulting code easier to read.

For example:

  * 71df678 - universal-windows: Use CreateFile2:
     * also introduces a new wrapper so that call-sites look the same
everywhere
  * 2635ec6 - universal-windows: Add helper for GetFileAttributesW:
     * same as above, introduces a new wrapper

The biggest commit (+71) is:

  * 2f35d8a - universal-windows: Implement temp_directory_path():
      * environment variables no longer exist (so getenv("TEMP") does not
work anymore), however the application model introduced in winrt has a
getter for the application specific temp directory, in order to be able to
compile this on VS2015 I opted for using WRL rather than C++/CX (see
separate discussion about how VS2015 is broken when compiling C++/CX from
the command line) this makes this commit balloon from 1 line to 71 :/

To put that in perspective, the line count for adapting filesystem to
> Android was +3 -1. Worse yet, the changes touch many different functions in
> the code, so the analysis of the changes is complex and time consuming.
>
>
I understand that this will take some time :-)

> I really do not want to apply a change of that magnitude. It is also
> suspicious that all the changes are too the operational code. Why are there
> no changes to test code or documentation?
>

Thanks, I will add compilation fixes for the tests and figure out where the
documentation needs updating or clarifying.

>
> Have you talked with Steve Gates from Microsoft? He seems to be leading the
> effort to adapt boost libraries to winrt so may know who to talk to about
> universal apps.

I talked to him a couple of months ago. But nowadays his email
@Microsoft.com bounces and from other softies I hear it seems he has left
the company. I have reached out to OSG to figure out if somebody else is
working on this but I am still waiting for answers.

> Surely Microsoft does not expect developers to make such
> massive code changes to adapt their libraries.

In general the differences between universal apis and traditional apis get
smaller if we target a newer windows version (e.g. increase our requirement
for _WIN32_WINNT to 0x0A00 [win10]). However in this particular case I do
not think we want to nor that it would make a difference (CreateFile[Ex]
and e.g. FindFirstFile seem to be gone even when targeting
_WIN32_WINNT=_WIN32_WINNT_WIN10).

> There is a need to abstract
> away more of the differences between traditional Windows API's and
> Universal app API's.
>

Can you clarify what you mean? I am willing to make whatever changes or
refactorings you want me to.

>
> Boost.Filesystem has suffered for years from lack of maintenance effort
> while I worked on the Filesystem TS. Now that the TS is done,
> Boost.Filesystem is getting maintenance effort again and 1.60 will have a
> lot of fixes. But there are still many high priority issues outstanding,
> and they get priority.
>

That makes sense. If I can lend a hand with anything give me shout.

Thanks,

Mikael