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Re: Need a module name... Transaction support for Storable file objects

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David Muir Sharnoff
November 14, 1999 14:08
Re: Need a module name... Transaction support for Storable file objects
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* Andreas J Koenig says ...
*  > On Fri, 12 Nov 1999 16:47:32 -0800 (PST), David Muir Sharnoff <> said:
*  > I've just written a module that does transactions.
* Great!
*  > It works in the following environment:
*  > 	Hash-based objects which are stored one-per file using Storable.
*  > It's multi-user and will not deadlock.  Transactions can span objects.
*  > What should I call it?
*  > 	Storable::Transaction
* This looks best to me.
*  > 	Object::Transaction
* If you can support multiple marshaling modules in such way as MLDBM
* does, then this is better, of course.
*  > 	Record
*  > 	Record::Multiuser
*  > 	File::MultiStorable
* Neither Record nor File "feel" right for my understanding. They seem
* to broad to me.

Andreas: how about FileObject::Transaction?

I've taken a look at what MLDBM does.  

I could do that too, but I don't have time right now.   It would be
much better if the multiple-marshalling problem could be solved 
generically and then I could just use the generic solution.

I took a whack at it long ago with my never-published
stuff.  Maybe someday...

There are a couple aspects to all of this:

    1.  How to choose underlying modules.  MLDBM co-opts the 
	import method to set module-wide parameters.

	I think we need a better general idiom for passing parameters
	into a module.

	How about a new package 'Customize' that does what Exporter
	currently does but also parses out option assignments
	in the use line:

	    use MDLBM qw(Serializer=Storable)

	There aren't going to be many functions with an '=' in their
	name so this should be fairly safe.

	For the module using Customize, the interface could look 
	something like:
		package MLDBM;
		@ISA = qw(Customize);
		@EXPORT = qw()
		@CUSTOMIZE = qw($Serializer=FreezeThaw $UseDB=File_SDBM $DumpMeth);

	Default values set by Customize when not specified with the use
	line and not previously specified by an earlier use of the package.

	A further refinement would be to have an optional function per
	customizable variable that is called by Customize.

		sub Serializer 
			my ($val) = @_;
			@mySerialize::ISA = ($val);
			require "$";

		later ...
		serialize mySerialize ($ref)

    2. 	Common interfaces to all the marshalling code.   In MLDBM,
	there is custom interface glue for each of the published 
	marshalling modules.  The interface glue provides a common
	interface of 'serialize' and 'deserialize'.

	This interface glue varies in complexity.

	I would like to propose that all of the marhsalling modules 
	export a common set of identical interfaces.   

	This should be too hard as Raphael Manfredi has already 
	written the glue...  It "just" needs to be moved into the various

I realize I'm suggesting other people do some work here.    I would be
happy to build Customize, but only if there is some agreement that it's
a Good Thing(TM).

I'm also happy to retrofit my as-yet-unnamed 
transactions-on-dumped-references-virtual-class package to whatever
standard emerges.



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