Re: PalmDB requests and bug report

On Tue, 26 Sep 2006, "Jeff Mikels" wrote:

> I'm having a problem with the crackPalmDate function
>
> (I'm using svn code)
>
> PILOT_TIME_DELTA = 2082844800L
> def crackPalmDate(variable):
>        if variable == 0:
>            return None
>        else:
>            return datetime.datetime.fromtimestamp(variable-PILOT_TIME_DELTA)
>
> I often get a ValueError because variable-PILOT_TIME_DELTA is sometimes a
> negative number. I've changed the code to be...
>
> PILOT_TIME_DELTA = 2082844800L
> def crackPalmDate(variable):
>        if variable == 0 or variable < PILOT_TIME_DELTA:
>            return None
>        else:
>            return datetime.datetime.fromtimestamp
> (variable-PILOT_TIME_DELTA)
>
> Is this a problem?

No, I don't think so, except that if the variable is before the 
PILOT_TIME_DELTA surprises could possibly happen in the Palm...

The reasoning behind my code (and it could be flawed), is that we want to 
know if there really wasn't a value there, like in SQL. So since I didn't 
think that the value would ever be zero (or below zero), using zero for 
NULL seemed like a perfect solution.

If that is not true, then we may need to rethink how things work.

Can you send me a patch with your changes so I can incorporate it?

Do make sure you have the latest code from SVN, I haven't changed it for a 
few weeks, but it's best to make sure you have the latest.

>
>
> Additionally, I'd like to create a "plugin" for the todo database, but I'm
> not sure how to go about doing it. The Base Plugin class is working
> perfectly but the payload needs to be decrypted properly. How can I create a
> plugin that only overloads the payload functions and have it loaded when
> necessary?
>

Well, I like plugins that are loaded automagically and that can be 
distributed separately, but in this case, I decided to keep it simple and 
have you declare the plugin to the code.

I also figured that we would just roll the plugins (not created by me) 
into the release, since just about anything someone makes will be useful 
to others.

[ If you use the library for something proprietary, you would just call 
the plugin notification code, and keep your code separate. ]

In the file PluginManager.py, you will find the functions 
registerPDBPlugin and deRegisterPDBPlugin. These are the functions you use 
to register your plugin with the framework.

At the bottom of the file, I use the standard functions to register my 
Progect plugin.


Now, I'm not really sure what you mean by decrypted.

If you mean you need to translate the XML that *would* have been generated 
into something more useful, the code knows how to apply XSLT stylesheets 
for you; both coming and going. It can also do some simple transformations 
like gzip.

If you need to output to say a binary or text format, I think it can be 
done, but I would have to look at the code again to explain how.


I really think I misdesigned the plugin somehow as well, but I can't 
really describe what I mean except to say this (because I haven't thought 
it through yet):
* Some classes do more than one thing - very bad
* The symptom is that the plugin is difficult to use.
* I expect that writing/reading formats other than XML will 
be more difficult than it should be (as in binary or text).


If you can describe what you are doing to me, then maybe I can give you 
some suggestions.

I'm going to have to redesign the code _again_ because of not getting the 
plugin code right, but I will try and remain compatible, or at least make 
it so much easier to use that it's not hard for you to update your code.


If you mean how do I crack the Palm task format, I can certainly help you 
with that too. Basically the plugin you create returns an object that 
knows what to do with the raw data as passed in by the framework.

You will need to find documentation on the Palm task format, I am pretty 
sure it can be found easily with Google.

In this case, you would probably just subclass the default plugin so that 
it returns a special Task object that knows how to crack the payload for 
tasks, and puts the values into a dictionary.

I believe the class ProgectRecord in plugins/ProgectPlugin.py is the 
closest thing to what you want. And the important method to create is 
_crackPayload.

The problem is, that the Progect format is quite complex, and we are 
forcing a tree into rows. So the Progect class is probably not a good 
example of how to do something simple (or not a good example at all...).

For something like the task database, you should have almost _no_ work to 
do, and so don't let the extreme complexity of the Progect plugin scare 
you off.

I can't predict how much work cracking a task would be, but I would hope 
it would be under a hundred lines of Python code all told, and simple code 
at that.

Generating and reading the XML would happen automatically if I remember 
correctly, so the big problem is being able to crack and pack the task 
format. (that is, the payload, because we crack the record header for 
you).

I would be more than happy to give you a hand with this task, while I am 
overloaded at work for the next day or so, perhaps we can talk via IM or 
on the phone. Even email would be fine, if you can help me understand your 
problem a little better.

I can then explain how I think it can be accomplished easily with the 
framework.

I will certainly try to do this for anyone who wants to use the framework, 
but having the task format converted to and from XML is an important 
feature for the framework and is therefore a priority for me.


Rick

>
>
>
> On 9/7/06, Rick Price <[email protected]> wrote:
>>
>> Okay, I just managed to get the Python PalmDB library to go from a Progect
>> file to XML and back again without dropping anything really obvious.
>>
>> Anyone who wants to check out the Subversion code is welcome to do so.
>>
>> I think I need to do a major rewrite at some point in the next little bit,
>> but first I will setup some conversions to popular programs that
>> read/write XML.
>>
>> First on the list is going to be treeline since I use it right now and the
>>
>> format seems to be basically sane.
>>
>> I will then probably try to do something with Omni Outliner for the Mac.
>>
>> That will probably require fixing a bug in the library that seems to show
>> up on the Mac.
>>
>> After that, I will see what I can do based on popularity.
>>
>>
>> Once I have treeline support working, and it's not too ugly to run, I will
>> make a release of Python PalmDB so people can start to use it.
>>
>> I will release again I would guess after I get Omni Outliner support
>> working.
>>
>> Any questions, just email me.
>>
>> Rick
>>
>>
>>
>>
>> Remember to visit Polls, Files and Bookmarks sections at
>> http://groups.yahoo.com/group/progect. You are welcome to vote, upload
>> your files and submit bookmarks.
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>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
> -- 
> Jeff Mikels
> leading people one step closer to Jesus
> http://jeff.mikels.cc
> http://thesouthsidechurch.org
>
>
> -- 
> Jeff Mikels
> leading people one step closer to Jesus
> http://jeff.mikels.cc
> http://thesouthsidechurch.org
>
>
> [Non-text portions of this message have been removed]
>
>



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