[saga-rg] Fwd (schuett at zib.de): Re: SAGA Strawman API

[Andre Merzky]

Hi group, 

Thorsten sent me some feedback to the strawman API.  Since
it is in german, I'll translate it to english for the list.
Some parts I leave out: those which point out small obvious
errors like spelling etc, which I just corrected in the doc.

Thanks for the comments, Thorsten!

On Friday 20 May 2005 18:47:11, Thorsten Sch"uett wrote:
> 
> Mal abgesehen davon, dass ich noch nie von SIDL gehört habe ...
> 
> - Warum brauche ich im Package NameSpace ein interface NSDir? Sollte das Ding 
> nicht Directory heissen?

Q: Why does the package NameSpace need a interface NSDir?
   Shouldn't that be named Directory?

A: It WAS named directore before, but we thought Dir to be,
   well, shorter, w/o loosing meaning.  Hmm, I prefer Dir
   for beeing shorter, but have no strong opniion about it.
   Others?


> - Ist isFile und isLink nicht wieder arg File spezifisch? In einem LDAP-Baum 
> hasst du bestimmt andere isXXX-Funktionen. isDir kann bleiben. Gibt es Links 
> in jedem Namespace?

Q: Isn't isFile and isLink too FILE specific?  In an LDAP
   tree you might find completely different isXXX methods.
   isDir is ok.  Are there inks in all namespaces?

A: isFile _sounds_ file specific, but that is a naming
   problem here.

   I have to elaborate on this somewhat, sorry.

   Once we had a NSDirectory and an NSDirectoryEntry
   interface.  The latter one was basically empty, but in
   any package implementing NS, that would get filles.  E.g.
   a physical file namespace would have a physical file as
   NSDirectoryEntry.

   Since that interface was empty, we got rid of it for now
   (just to be minimalistic).  We figured: if we find good
   reasons (say: methods) for it to exist, we just include
   it again.

   Now that left is no good choice for naming the isEntry
   w/o creating confusion, so we named it isFile.
   Basically, that checks if the entry is, well, an entry.
   So, maybe the name _should_ return after all.

   For links: most name spaces have link.  If not, then the
   is does not hurt.  However, that method seems more
   related to the namespace concept than to its physical
   representation - thats why it is in the NS interface.
   Does that make sense?


> - Impliziert der openDir-Call irgendwas für das Current working directory von 
>   der neuen Directory-Instanz?

Q: Is the openDir call indicatind anything in respect to the CWD of
   the new directory?

A: Good catch!  Yes, the CWD is pointing to the opened
   directory.  I changed the doc.


> - Was ist das Current working directory von NSDir("/")?

Q: what is cwd of NSDir("/");

A: "/".


> - Irgendwie sind die Flags merkwürdig. Ich könnte ein Flags-Array mit Create 
> und NoCreate erzeugen. Es würde dann zwar ein Exception geworfen, aber sowas 
> kann auch der Compiler überprüfen. Lass doch die NoXXXX Flags weg und mach 
> flags zu einem set<openFlags>. Dann gibt es auch keine doppelten Flags. Und 
> wenn ihr schon numerische Werte für die Flags einführt, gestalte sie doch so, 
> dass man auch ein einen Integer und Bit-Arithmetik in einem Binding verwenden  
> kann.
> enum openFlags{
> Create = 1,
> Excl = 2,
> Truncate = 4,
> Append = 8,
> Lock = 16
> };

Q: Flags are strange: I could create a flagg array with both
   'Create' and 'NoCreate'.  Well, thats would give an
   exception, but thats something which could be catched by
   the compiler.  You could leave out the NoXXX flags, and
   change the flags to set<openFlags>.  the there are no double
   flags.  And if you go for numeric values, you could do
   the usual bit arithmetik thingie...

A: I agree.  I can't for sure remember the rationale for the
   current notation -- but I think we left that to the
   language binding.  So, in C we would do what you suggest.
   

> - Ist irgendwo definiert, wie gross ein long sein muss? Gerade für Grids 
>   sollte getSize mindestens 64-Bit zurückgeben.

Q: Is there any definition for sizeof (long)?  In particular
   for Grids, getSize should return at least 64 bit.

A: SIDL defines long to be 64bit.  I will put the SIDL
   documentation on the WIKI.


> - read: Posix kennt kein EndOfFile-Error. Dann wird einfach 0 zurückgegeben.

Q: in posix, there is no EOF error - just returns 0.

A: Oops!  removed.


> - interface Attribute: Komischer Name, beschreibt das Interface nicht eher 
>   eine "Description" o.ä.? removeAttribute wird nicht genauer beschrieben. Mit 
>   eurem Interface kann man zu einem Key nicht mehrere Values haben. Schade.

Q: Interface Attributes: strange name, isn't that rather a
   description or such?  removeAttribute is not fleshed out.
   You can't have multiple values for one key - a pity.

A: Hmm, maybe we didn't transport the idea well enough.
   Think physical files: attributes would be for example:
   file size, file type, last mod time, owner, ACL etc.
   You don't have two values for size.  If you have more
   than one item to one key (acl), you have vector
   attributes for these.

   I am not sure what you mean with description, or with
   multiple values in that context.  Do you have an example?

   removeAttribute: Oops, fixed.

> - In den Beispielen taucht manchmal "Context" auf. Im Text wird es glaube ich 
> nicht erläutert. Könnt ihr die Dinger nicht bitte komplett eleminieren?

Q: In some examples appears a 'context' - this is not
   elaborated elsewhere in the text.  Cant you remove them
   completely?

A: A context is supposed to be a SAGA session handle.  But,
   you are right, until they are fleshed out in the spec, they
   should go away in the examples.

Thanks again, 

  Andre.

> Thorsten

----- End forwarded message -----

-- 
+-----------------------------------------------------------------+
| Andre Merzky                      | phon: +31 - 20 - 598 - 7759 |
| Vrije Universiteit Amsterdam (VU) | fax : +31 - 20 - 598 - 7653 |
| Dept. of Computer Science         | mail: merzky at cs.vu.nl       |
| De Boelelaan 1083a                | www:  http://www.merzky.net |
| 1081 HV Amsterdam, Netherlands    |                             |
+-----------------------------------------------------------------+