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Re: [ddlm-group] Relationship of CIF2 to legacy platforms
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] Relationship of CIF2 to legacy platforms
- From: David Brown <idbrown@mcmaster.ca>
- Date: Thu, 19 Nov 2009 09:52:42 -0500
- In-Reply-To: <279aad2a0911181834j3c93b0f9q7bca234514df2d57@mail.gmail.com>
- References: <C71DF6D4.12389%nick@csse.uwa.edu.au> <4AFC3C0B.7060404@niehs.nih.gov><279aad2a0911181834j3c93b0f9q7bca234514df2d57@mail.gmail.com>
I have no strong views on line length, but the arrguments for
keeping them seem a little stronger than those for abolishing them. I
have no views at all on how long the lines should be other than to note
that Acta Cryst. programs get upset if there are more than 80
characters in a line. David James Hester wrote: We should resolve the Fortran line length issue as I think we've got enough information on the table - could those who haven't indicated their preference please vote either (1) CIF2 should have a maximum line length specified or (2) no line length should be specified. For bonus points, you can indicate what this length should be. So (including Nick's recent email) I count the votes as: (1) Herbert (>=2048), Nick (2048), James (4096) (2) Joe I've added my vote to the fixed line length simply because I accept Herbert's argument that legacy Fortran programs are actually important in the crystallographic world, and a restriction on line length does not impose a burden on CIF readers. It also imposes a bit of discipline on CIF writers and helps to produce a readable file. On Fri, Nov 13, 2009 at 3:47 AM, Joe Krahn <krahn@niehs.nih.gov> wrote:Nick Spadaccini wrote:On 3/11/09 12:53 AM, "Joe Krahn" <krahn@niehs.nih.gov> wrote:Herbert, I am only suggesting that maintained Fortran code ought to be able to utilize F2003 STREAM I/O, supported by current versions of GFortran, Intel Fortran and Sun Fortran. Of course, I probably am not considering all of the issues. STREAM I/O avoids the need for a fixed maximum record length, but even the newest Fortran compilers have very limited UTF-8 support. Even with STREAM I/O, it is not trivial to count trailing blanks as significant. Maybe the biggest problem is UTF-8. IMHO, it makes sense for UTF-8 to be an optional encoding, rather than just declaring CIF2 is all UTF-8. ThisNot sure what you gain by doing this. If it is pure ASCII only then the declaration of UTF-8 inhibits nothing, since ASCII is a subset. If it is not pure ASCII, then it needs to be UTF-8. I can't see how knowing in advance that it is a subset of UTF-8 or possibly the full set of UTF-8 gives you anything. cheers NickA compiler/language not aware of UTF-8 could avoid errors by rejecting CIF files that contain UTF-8. However, I think the approach being taken is just to allow implementations to restrict usage, rather than put it in the specifications. For example, the plan seems to be that DDL/dictionary definitions will be used to avoid UTF-8 in data names, where it is most likely to be a problem. So, you are right: there is no reason for the CIF2 syntax to make UTF-8 optional when the dictionaries can restrict characters to the ASCII subset. The other potential legacy issues I know of are fixed maximum line lengths, and significant trailing blanks. Dictionary definitions cannot avoid these. It might be possible to take a similar approach, by avoiding them by implementation conventions rather than making it part of the spec. If these are only going to be an issue for a few more years, it would avoid having to make another syntax change in the near future. My main interest here is to avoid incompatible implementations. I also think that Fortran, and any other line-oriented I/O software, should be able to do stream-oriented I/O in the near future. Joe _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group |
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