220 28295 <2d8cf6fa-76f0-4147-bada-771f836bc435@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: =?UTF-8?Q?Jens_=C3=85kerblom?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Filesystem Library and Standardized Paths Date: Tue, 20 Sep 2016 01:25:33 -0700 (PDT) Lines: 202 Approved: news@gmane.org Message-ID: <2d8cf6fa-76f0-4147-bada-771f836bc435@isocpp.org> References: <316e66e9-764b-40da-bffc-e0ce2ed75ddd@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4536_1518325317.1474359933184" X-Trace: blaine.gmane.org 1474359958 28197 195.159.176.226 (20 Sep 2016 08:25:58 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 20 Sep 2016 08:25:58 +0000 (UTC) Cc: mwoehlke.floss@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC2YT3FOXEIBB7XEQO7QKGQEFUNHR7Q@isocpp.org Tue Sep 20 10:25:54 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it0-f70.google.com ([209.85.214.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bmGMy-0004qD-L1 for gclcip-std-proposals@m.gmane.org; Tue, 20 Sep 2016 10:25:36 +0200 Original-Received: by mail-it0-f70.google.com with SMTP id e20sf33112430itc.3 for ; Tue, 20 Sep 2016 01:25:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=6FcGjyrhzjkRUBctxdq4Hc+DMx86uHo9jYc3j/9dsls=; b=oKHAL6OJFk8ffzZWEr82vyOBaZOkgL/5mhnKMdgEot1b4WXEGnuwhZ+jDT6eG9A6cP t3qXqIVi4wqnr0LLhbCHx8Mn8nmFE66zsHn8zWFTC111JOcdfZfmz8E5rdNVJM0KZzpd R6NBqNxX19Yqw+z3KDlXpY7YUI+oNw2vsNIUe1E7EtlqIWQay9ThPFUvL5XVD4qLz3TH 8Pd3UHMmQkcwGgqttK/+mYn0EVFzsgIQKVte5YMylzEEpAcpvlY9ysVyXyMIdL+3+KeT Bu86VNv/tG38xfZDxU2HOhOAn0AoNlYjhNhZZfrUiSewOmO2nKXqEf9o0QSXeWoL/sTg dI7w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=6FcGjyrhzjkRUBctxdq4Hc+DMx86uHo9jYc3j/9dsls=; b=Yvkbi6azbXogIXD6TJAHCVfeBfXVp/CWzgFsmHfpT9PmMAun8l0sFlhmaWY+XiTCzf AGtxmwkDNtisl5QEyLId2LsAYNnbRdzBKc/W086AxE4gy2OWkMKH2+mFiRmhexYPbl15 E6LK+5QQe+B9j4DpkqPGpvAIZoCAQr0nCFPTfNBxzG6Z0rZNp2nu6ybjWUKY10V51gP9 FfrIdLeWX8CCSYEnIrRgtxyaSEeWoL85RKXvmSs9uW9mHlLq70ejC5ukHuIsFObX42OD E1bIfrNMJYR8UMWdGba2shxKA7ehn1YekCAjJAnBcmfg6iy+sOMtKFw0IhuJU2GxT7Oq y1Fw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:x-original-sender:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=6FcGjyrhzjkRUBctxdq4Hc+DMx86uHo9jYc3j/9dsls=; b=eTVOq4TcA7JOOnKWFxIgmRDsBvC0J3CoPoG8AuPnSbcQQLnL1x82tva/VkQjTd+OMR mZpNsVPDNuwU3Cc7PsADc7O0hjFRn69LcbsM+FGFhM628wbK3nLf8FpD9JN5yAiM2EUc MmkXF7lBlN/bExfftzQffryvr4SeF4aEzlobmvKmx1nN+krkt0LtQsiSmbQPiOZUnIY1 sZ83AeP9u4LsB/1spv0ft77u7wJIUfsyxGHfVVJGvesNGStkbXclK9qvujNjKwglYKmH Yl2Q4mqxdqz0fsCkUBOEK0arXhBPJzhU98c6sP3jqQfhSmQrn4/DUf2/B1gET4LLy9Fs QSaQ== X-Gm-Message-State: AE9vXwMz3i4mCdOV3crfQYGy5/UUd7UO2dhaO8x2Wi0LRc0ixSyCgKR5V3pufIhqIiWDAw== X-Received: by 10.36.60.15 with SMTP id m15mr655647ita.5.1474359937863; Tue, 20 Sep 2016 01:25:37 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.211.20 with SMTP id n20ls1986488itg.12.canary; Tue, 20 Sep 2016 01:25:34 -0700 (PDT) X-Received: by 10.36.60.150 with SMTP id m144mr60920ita.1.1474359934369; Tue, 20 Sep 2016 01:25:34 -0700 (PDT) In-Reply-To: X-Original-Sender: akerblom.jens@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:28295 Archived-At: ------=_Part_4536_1518325317.1474359933184 Content-Type: multipart/alternative; boundary="----=_Part_4537_2143730215.1474359933185" ------=_Part_4537_2143730215.1474359933185 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable > > These may be simplifications. I would compare with existing prior art,=20 > e.g. http://doc.qt.io/qt-5/qstandardpaths.html.=20 > Thank you for the QStandardPaths link, did not know that existed. This is= =20 exactly what I'm hoping would end up in the standard (or at least some of= =20 the paths). As I see it, any file operations in C++ must either use=20 current_path() or do their own platform dependent path lookup (or use third= =20 party libraries to do it for them). Shifting the responsibility to write=20 these path lookups to the standard library writers would thus make it=20 easier to write platform independent code in my opinion. Do you think this is worth taking forward by writing a proper proposal? On Saturday, September 17, 2016 at 6:12:10 PM UTC+3, Matthew Woehlke wrote: > > On 2016-09-11 11:19, Jens =C3=85kerblom wrote:=20 > > Hello there,=20 > >=20 > > I've been looking through the proposed C++17 Filesystem library and=20 > thought=20 > > it would be a nice add-on to have common paths. The only path I see tha= t=20 > is=20 > > already present is the *std::filesystem::temp_directory_path*. The=20 > > directories of interest (as I see) would be=20 > >=20 > > - *executable_directory_path*, *installed_directory_path* or maybe a= =20 > > better name, *bundle_directory_path*, directory where the executable= =20 > is=20 > > being run / has been installed. Assumed to be read-only.=20 > > I don't think you can implement this without platform support. That=20 > support *might* already be available on common platforms, but then again= =20 > it might not.=20 > > Implementing it for example on Linux requires digging around in /proc.=20 > Specifically, you need something like https://github.com/gpakosz/whereami= ..=20 > > > > - *userdata_directory_path*, directory where current user stores=20 > data,=20 > > "My Documents" on Windows for example. Assume permission required to= =20 > write=20 > > and read.=20 > > - *cache_directory_path*, directory to data that persists longer tha= n=20 > in=20 > > *temp_diretory_path*, can be removed by OS if deemed necessary.=20 > > "Library/Cache" on iOS for example. Assume write and read permission= ..=20 > > - *appdata_directory_path*, directory where the application can stor= e=20 > > persistent data not to be shared with other application.=20 > > "/data/data/" on Android for example. Assume write and= =20 > read=20 > > permissions.=20 > > These may be simplifications. I would compare with existing prior art,=20 > e.g. http://doc.qt.io/qt-5/qstandardpaths.html.=20 > > --=20 > Matthew=20 > > --=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/2d8cf6fa-76f0-4147-bada-771f836bc435%40isocpp.or= g. ------=_Part_4537_2143730215.1474359933185 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
= These may be simplifications. I would compare with existing prior art,
e.g. http://doc.qt.io/qt-5/qstandardpaths.html.

Thank you for the QStandardPaths link, did not know th= at existed. This is exactly what I'm hoping would end up in the standar= d (or at least some of the paths). As I see it, any file operations in C++ = must either use current_path() or do their own platform dependent path look= up (or use third party libraries to do it for them). Shifting the responsib= ility to write these path lookups to the standard library writers would thu= s make it easier to write platform independent code in my opinion.

D= o you think this is worth taking forward by writing a proper proposal?
<= br>On Saturday, September 17, 2016 at 6:12:10 PM UTC+3, Matthew Woehlke wro= te:
On 2016-09-11 11:19, Jens = =C3=85kerblom wrote:
> Hello there,
>=20
> I've been looking through the proposed C++17 Filesystem librar= y and thought=20
> it would be a nice add-on to have common paths. The only path I se= e that is=20
> already present is the *std::filesystem::temp_directory_path*= .. The=20
> directories of interest (as I see) would be
>=20
> =C2=A0 =C2=A0- *executable_directory_path*, *installed_directory_p= ath* or maybe a=20
> =C2=A0 =C2=A0better name, *bundle_directory_path*, directory where= the executable is=20
> =C2=A0 =C2=A0being run / has been installed. Assumed to be read-on= ly.

I don't think you can implement this without platform support. That
support *might* already be available on common platforms, but then agai= n
it might not.

Implementing it for example on Linux requires digging around in /proc.
Specifically, you need something like https:/= /github.com/gpakosz/whereami.

> =C2=A0 =C2=A0- *userdata_directory_path*, directory where current = user stores data,=20
> =C2=A0 =C2=A0"My Documents" on Windows for example. Assu= me permission required to write=20
> =C2=A0 =C2=A0and read.
> =C2=A0 =C2=A0- *cache_directory_path*, directory to data that pers= ists longer than in=20
> =C2=A0 =C2=A0*temp_diretory_path*, can be removed by OS if deemed = necessary.=20
> =C2=A0 =C2=A0"Library/Cache" on iOS for example. Assume = write and read permission.
> =C2=A0 =C2=A0- *appdata_directory_path*, directory where the appli= cation can store=20
> =C2=A0 =C2=A0persistent data not to be shared with other applicati= on.=20
> =C2=A0 =C2=A0"/data/data/<package_name>" on Androi= d for example. Assume write and read=20
> =C2=A0 =C2=A0permissions.

These may be simplifications. I would compare with existing prior art,
e.g. http://doc.qt.io/qt-5/qstandardpaths.html.

--=20
Matthew

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/2d8cf6fa-76f0-4147-bada-771f836bc435= %40isocpp.org.
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