Re: [ddlm-group] CIF header

I agree with Brian's suggestion.  Can other participants also indicate
their agreement or alternative suggestions?

James.

On Fri, Nov 20, 2009 at 11:15 PM, Brian McMahon <bm@iucr.org> wrote:

Is there a reason why it can't be #!, to make it consistent with other *nix
based directives.

As James says, #! is normally understood by Unix shells to specify
an appropriate shell interpreter, not quite what we're aiming for here.

A characteristic initial set of bytes (file 'magic') is often used
by GUI file managers and other generic file-handling software to
associate icons or applications (in association with, or sometimes
competing against, the use of a filename extension). We use this
approach to identify the type of file uploaded in our submission
system. It's useful for that initial byte sequence to be (a) short
to facilitate rapid scanning, (b) specific to an individual file type.
For that reason we suggested for CIF 1.1 the magic string
     #\#CIF_1.1
For CBF it is
     ###CBF: VERSION

I recommend #\#CIF_2.0 to be consistent with version 1.1 and so that
generic file magic handling can map all #\#CIF_ strings to files of type
"cif". (A sophisticated file manager could extend the scan to allow for
different icons to be associated with version 1.1 and version 2 CIFs.)
It seems a pity from the viewpoint of neatness that the CIF and CBF
magic strings aren't more similar in structure.

Brian

On Fri, Nov 20, 2009 at 02:09:56PM +0800, Nick Spadaccini wrote:

We don't need an extra character, a single hash would suffice, but I guess
an extra character my uniquely identify it as the CIF header to a parser,
rather than it as just a comment. An extra character also moves you away
from an ordinary comment which is smart, to a smart comment which has its
own unique tag. I am NOT a fan of smart comments, or comments which can be
smart, but they seem to be to modus operandi of many systems.

On 20/11/09 1:59 PM, "James Hester" <jamesrhester@gmail.com> wrote:

Wouldn't this cause a UNIX-style OS to try to execute 'CIF2' if
someone accidentally typed the filename in a command context?  This is
not a huge problem in that it will otherwise attempt to execute
'data_xxxx', and only if the file is executable.

I guess I don't understand why we need an extra character after the
hash.  If we really do need an extra character, why not just another
hash?

On Mon, Nov 9, 2009 at 7:30 PM, Nick Spadaccini <nick@csse.uwa.edu.au> wrote:

On 30/10/09 11:47 PM, "Joe Krahn" <krahn@niehs.nih.gov> wrote:

A directive embedded in an initial comment really does make sense,
because it is irrelevant once the correct parser is selected. It might
make sense to add a specific 2nd character, similar to the POSIX shell
#!. For example, the STAR format could define an initial line beginning
with #% as parsing directive rather than just a plain comment. That
makes the abuse of a comment line as a bit less of a hack.

Is there a reason why it can't be #!, to make it consistent with other *nix
based directives.

cheers

Nick

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