looking for way to include many times some .py code from anotherpython code

Steve Holden steve at holdenweb.com
Wed Mar 9 00:43:16 CET 2005


Martin MOKREJŠ wrote:
> Steve Holden wrote:
> 
[...]
>> I will be *very* surprised if you can't get a much better (i.e. easier 
>> and more efficient) solution by stepping back from the programming 
> 
> 
> Hmm, I'm not convinced, but I'll put few more words here then. ;)
> 
>> details for a moment and explaining what it is you are actually trying 
>> to achieve in user-space.
>>
>> Can you describe the problem you are trying to solve, rather than the 
>> solution you are hoping to adopt?
> 
> 
> User inputs data through html forms, data has to be quality-checked
> and strored into mysql. Later, data is read from mysql and presented
> through web. There's nothing special in it, just that the tables
> describe a lot of specific experimental parameters. Tables do reflect
> type of informations, so they group the data into logical units - so
> tablename reflects the data contained.
> 
> In general, there are two types of data, hence my X and Y objects.
> The underlaying data at some time point go into sql tables. Before that
> happens, the data == variable contents are checked that they contain
> expected values (in some cases enumerated values, in some cases integers,
> sometime chars and only about 6 blobs). I spent a year developing the
> database schema and php code, the schema is nearly optimal. I got bored
> by the php code, as it was partly developed by a lazy guy (lazier than 
> I'm).
> I went fot python - to have better error handling, have not only web app,
> but reusable code for standalone application (html forms can be replaced
> by any tcl/tk widget for M$ Windows). Sql transaction I have added to
> the php code, but anyway it sucks to work with it further.
> 
> My idea is to check some of the values while instantiating, as I get it for
> free (assigning either to a default value or raising an exception when
> variable is empty). In most cases this is not enough, and I have to type in
> the allowed values.
> 1. In case of enumerated types, I hope to find a tool
> able to read sql files and able to extract column definitions. In this
> particular case, the program would dynamically read allowed ENUM values,
> so whenever sql table is altered, the program will recognize new value
> allowed.
> 2. In most other cases, the values are simply some kind of string, and
> .find() et al. will suffice.
> 3. In case data was read from mysql, I can verify that foreign keys refer
> to what they should refer.
> 
> OK, I get the data written to mysql. I can fetch it back, and want to dump
> it into xml and present on web/(local gui).
> 
> I have the claases corresponding to all tables as superclasses of X and Y
> as necessary. I went to ask on this list how to assign the variables easily
> because parts of the code are almost identical. I believe this has been
> answered quite well.
> 
> I believe the approach using classes corresponding to every single table
> is right, when using them as superclasses for those two, practically
> used objects: X and Y.
> 
> To print the output on web or any gui, I think I'll use the xml output
> and just parse it. I need xml anyway for testing, and definitely want
> to be able to construct the html/GUI output from the xml input - again,
> for testing. So the objects will more or less exist only to get the
> necessary checks done for those myriads of variables, which must be
> evaluated in current context. I'd get crazy if I'd store things into
> bsbdb -- I'm not going to remember that a[0] is table1, a[1] is table2,
> a[0][0] is the primary key called blah, a[0][22] is allowed to be equal 
> only to "foo" or "bar" ... and that if a[2][4] is defined (actually 
> number),
> the number is the key to search in c[key]. Simply, that's for what I use 
> mysql
> I don't want to invent the database schema in bsddb in python. ;)
> It's simply data, it must be read into variables in some objects, those
> object are groupped into just two superobjects. The superobjects define
> check-methods, define how to dump the it's data into xml, how
> to write (in which order) the values into mysql.
> 
> I'm sorry not to send in the sql schema + the code, but this is my phd 
> thesis. ;)
> 
> I'm very glad there's so many people interrested to help - not only - me.
> Thanks! Now I'm really looking forward how would you rework this thing.
> It's simple, easy, it's just sometime tedious as having 250 columns in 
> 20 tables
> simply makes you bored to type the code, after while.
> 
> The only think where I think I need help is, how to dump easily into xml 
> say object
> X, having variables a, b, c, where c is a ref. to object B, containing 
> variables p, q, r.
> 
>>>> B = obj()
>>>> setattr(B, p, 44)
>>>> setattr(B, q, "sdjahd")
>>>> setattr(B, r, "qew")
>>>> X = obj()
>>>> setattr(X, a, 1)
>>>> setattr(X, a, 2)
>>>> setattr(X, a, B)
> 
> 
>>>> print do_magick(X)
> 
> <X>
>    <a>1</a>
>    <b>2</b>
>    <B>
>        <p>44</p>
>        <q>sdjahd</q>
>        <r>qew</r>
>    </B>
> </X>
> 
>>>>
> 
I still don't really see why you have to store this thing as objects, 
but I appreciate that you can only give limited information and still 
retain the validity of a thesis.

My own usual approach in such situations is to use metadata to describe 
the structure and required processing of the data, as it's often much 
easier to write small amounts of relatively flexible data-driven code 
that it is to hard-wire all the logic around specific structures and data.

However you appear to have chosen your approach, so having made your bed 
you must now proceed to lie on it! :-) Good luck with the thesis.

regards
  Steve




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