🌐 Mailman 3 August 2006 - Python-list - python.org

Re: opposite of import
by John Salerno Aug. 3, 2006

Aug. 3, 2006

Simon Brunning wrote: > but for the fact that Python > stashes a reference to the module in (IIRC) sys.__modules__. And you > mess with *that* at your peril. ;-) According to Python in a Nutshell, references are stored in the dictionary sys.modules, but I'm not sure if it matters that it's not __modules__ instead (unless that also exists).

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Grammar parsing
by Paolo Pantaleo Aug. 3, 2006

Aug. 3, 2006

Hi, How can I write a pareser for a certain gramamr? I found PyPy that does it, is thare any other tool? Maybe something built-in the python interpreter? Thnx PAolo -- if you have a minute to spend please visit my photogrphy site: http://mypic.co.nr

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programming is hard
by placid Aug. 3, 2006

Aug. 3, 2006

Hi all, this site is contains code snippets for various languages and python does not have many code snippet posters. Just lettting you know http://programmingishard.com Cheers P.S: I have no connection with this site!

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Re: Windows vs. Linux
by Gerhard Fiedler Aug. 3, 2006

Aug. 3, 2006

On 2006-08-03 04:53:11, Sybren Stuvel wrote: >> Pretty much every production cost increase gets in the end paid by >> the consumer. With some localized changes, you may be lucky and >> don't buy any products that are affected, but with such a widespread >> change as this would be, it is more likely that almost everybody is >> affected close to average. > > You still don't tell me how I could be affected by a production cost > increase at a company I'm buying nothing from. You don't buy your gas as crude from Saudi Arabia oil well, do you? :) Their production cost increases may affect you nevertheless. There are very few products you buy that are only affected by costs generated in one company. Usually that's dozens, if not hundreds of companies in the chain. (That's not to say that all of them are relevant, price-wise, but it's more than one that's relevant, usually.) Take your pick, anything, and try to find out the price building chain. You may be surprised. Besides, you probably don't know whether it's not one of your direct suppliers who's affected. You're sure you don't buy from anybody running a Windows system? I'd bet against that, and I only bet when I know I win :) I'm not talking about something obvious like a 10% increase. An overall (average) 1% increase is easy to dismiss as not relevant -- but it's still 1%, if you add it up. (I'm not claiming it would be 1% though. Just an example number.) >> With that is also mostly the pressure gone to not increase -- >> because so many are affected that the few who are not happily >> increase the prices with the others. > > Either my English isn't as good as I thought, or that's simply > incomprehendable. Possibly the latter... I'll try again :) When there's a change in the cost structure of some companies, they try to pass that on through their prices. That's just natural. If the cost structure of a whole sector changes, that's easy, because all of them will want to increase by the same margin, and the cost structure of the whole sector remains the same. (See gas prices.) If almost all of a sector are affected, this still doesn't change (usually): the ones who are not affected often just go with the crowd and increase nevertheless, figuring they can gain more by increased margins than they would gain by increased market share due to lower prices. (There are all kinds of factors that affect this; not always a lower price gets reflected in a higher market share.) But they (or some of them) could also decide to stay at their lower price to gain market share. But if the production cost for 80% of a sector goes up, it may be that the 20% who don't have that cost increase stay low, but the average price of that sector still will go up. (Not everybody will move to the suppliers now with lower cost.) With that, the average production cost for companies that depend on that sector will go up. So there's an average hike anyway, even if some or all of the ones who don't have to increase actually don't. Gerhard

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Re: opposite of import
by Duncan Booth Aug. 3, 2006

Aug. 3, 2006

Gerhard Fiedler wrote: > On 2006-08-03 09:26:54, Simon Brunning wrote: > >>> import amodule >>> amodule.afunction() # Works fine >>> >>> del amodule >>> amodule.afunction() # Will die now >> >> Note that this doesn't get rid of a module entirely. Python will >> still holds on to the module, and if you just import it again at this >> point, it won't be re-executed - you'll just get another reference to >> the original module. > > Is that guaranteed, or is that just until the garbage collector has > removed the module (at some arbitrary point)? > It is guaranteed that simply deleting the module from the module which imported it won't be sufficient to throw it away as other references to the module will remain (in particular the list of modules used by the import mechanism to ensure you get the same module if you re-import it again in the future).

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opposite of import
by pranav.choudhary＠gmail.com Aug. 3, 2006

Aug. 3, 2006

Hi I am new to python. I wanted to know if there is an opposite of "import"

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Datetime question
by Lad Aug. 3, 2006

Aug. 3, 2006

In a datetime object I would like to change days and hours. Or in other words, I would like to copy this datetime object but increase days and hours. Is it possible? For example:If I have a datetime object like this datetime.datetime(2006, 8, 3, 14, 13, 56, 609000) I would like to make a new ,for example like this datetime.datetime(2006, 8, 12, 10, 13, 56, 609000) is it possible to do so? Thank you L

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Re: Grammar parsing
by Nicola Musatti Aug. 3, 2006

Aug. 3, 2006

Paolo Pantaleo wrote: > Hi, > > How can I write a pareser for a certain gramamr? I found PyPy that > does it, is thare any other tool? Maybe something built-in the python > interpreter? Check out Dave Beazley's Ply: http://www.dabeaz.com/ply/ . Cheers, Nicola Musatti

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need help of regular expression genius
by GHUM Aug. 3, 2006

Aug. 3, 2006

I need to split a text at every ; (Semikolon), but not at semikolons which are "escaped" within a pair of $$ or $_$ signs. My guess was that something along this should happen withing csv.py; but ... it is done within _csv.c :( Example: the SQL text should be splitted at "<split here>" (of course, those "split heres" are not there yet :) set interval 2; <split here> CREATE FUNCTION uoibcachebetrkd(bigint, text, text, text, text, text, timestamp without time zone, text, text) RETURNS integer AS $_$ DECLARE result int4; BEGIN update bcachebetrkd set name=$2, wieoftjds=$3, letztejds=$4, njds=$5, konzern=$6, letztespeicherung=$7, betreuera=$8, jdsueberkonzern=$9 where id_p=$1; IF FOUND THEN result:=-1; else insert into bcachebetrkd ( id_p, name, wieoftjds, letztejds, njds, konzern, letztespeicherung, betreuera, jdsueberkonzern ) values ($1, $2, $3, $4, $5, $6, $7, $8, $9); result:=$1; END IF; RETURN result; END; $_$ LANGUAGE plpgsql; <split here> CREATE FUNCTION set_quarant(mylvlquarant integer) RETURNS integer AS $$ BEGIN perform relname from pg_class where relname = 'quara_tmp' and case when has_schema_privilege(relnamespace, 'USAGE') then pg_table_is_visible(oid) else false end; if not found then create temporary table quara_tmp ( lvlquara integer ); else delete from quara_tmp; end if; insert into quara_tmp values (mylvlquarant); return 0; END; $$ LANGUAGE plpgsql; <split here> Can anybody hint me in the right direction, how a RE looks for "all ; but not those ; within $$" ? Harald

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Re: Is there an obvious way to do this in python?
by Bruno Desthuilliers Aug. 3, 2006

Aug. 3, 2006

H J van Rooyen wrote: > "Bruno Desthuilliers" <bdesth.quelquechose(a)free.quelquepart.fr> wrote: > > > |H J van Rooyen a écrit : > |> Hi, > |> > |> I want to write a small system that is transaction based. > |> > |> I want to split the GUI front end data entry away from the file handling and > |> record keeping. > |> > |> Now it seems almost trivially easy using the sockets module to communicate > |> between machines on the same LAN, so that I want to do the record keeping on > one > |> machine. > |> > |> I want to keep the "server" machine as simple as possible - just doing record > |> keeping on a stimulus response basis - I would prefer it to do one thing at a > |> time to completion because this style of operation, though limited in > |> performance, keeps a lot of hassles out of life - a transaction has either > |> completed, or it has not - recovery scenarios are relatively easy... > | > |IOW, you want a SQL DBMS. May I recommand PostgreSQL ? > | > > Looks like the way to go - after the argy bargy here in another thread seems > mySQL has no supporters left... Indeed, my choices would now be SQLite for simple things and PostgreSQL for more serious stuff... > |> Up to this point, I don't have a problem - my toy system can create a dummy > |> transaction, and I can echo it from the "server" machine, with more than one > |> "user" machine running - so I think it is feasible to have several tens of > "data > |> entry terminal" systems running, served by one not very strong machine. > |> > |> Now what I would really like to do is to differentiate between the 'User" > |> machines, so that some can do a full range of transactions, and others a > limited > |> range. > | > |Any decent SQL DBMS is able to handle this. It's kind of builtin... > > Yes - if you do the whole job on the server - > the architecture I have mind is > more like a banking terminal scenario - please see my reply to Simon (...) Done. And I still think that a CherryPy/PostgreSQL based solution is the way to go. > | > |> And I would like to make this flexible, so that it becomes easy to introduce > new > |> transactions, without having to run around updating the code in all the user > |> machines, with the concomitant version number hassles. > | > |Then you want a web front end. > > This seems to me to assume that the server does all the work Not necessarily. Of course most computations are done on the server, but what you describe here really feels like AJAX IMHO. Have a look at some Turbogears AJAX addons like Catwalk and ModelDesigner... > | > |> And I would like to do the whole thing in python > | > |You'll at least need bits of SQL (but SQLAlchemy may hide away most of > |it) and HTML (but there are some python packages that knows how to build > |HTML from declarative Python code). > | > > that is good news - which packages? http://divmod.org/trac/wiki/DivmodNevow http://divmod.org/trac/wiki/DivmodNevow/Athena http://starship.python.net/crew/friedrich/HTMLgen/html/main.html http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/366000 http://dustman.net/andy/python/HyperText/ http://pyhtmloo.sourceforge.net/ > |> - so my question is this - is > |> it possible to do the equivalent of dynamic linking? - i.e. if I keep a list > of > |> what a user is allowed to do > | > |In SQL : GRANT/REVOKE > > again - centric thinking - I really would like to change the bits on the client, > as I explained to Simon > > | > |> - can I somehow send him just the bits he needs to > |> do the job, without having to change the static code on his machine? > | > |HTTP/HTML. > | > > everybody says this Well, there must be a reason... > - I am being dragged, kicking and screaming... > > |> - it seems > |> to me that the eval() thingy could possibly do this for me, > | > |Err... I thought you wanted a reasonnably secure system, but I may have > |misunderstood. > | > > this is the guts of what I want - if eval is NFG then how do I implement such a > kind of "dynamic linking" of modules on the client? You may want to look at stuff like Pyro (Python remote objects). > |> by sending it data > |> that makes it do import statements followed by calls to whatever... - will > this > |> work, or is there a better way? > |> > |> Or has all this been done already? > | > |Yes, it's called a web frontend for a SQL DBMS. There's no shortage of > |Python frameworks to do this kind of things. > | > > I kind of wanted to avoid the web based stuff - the application data is so small > and trivial, in a sense. So why even bother writing your own transaction manager, dynamic client and protocol when the whole thing already exists - PostgreSQL, Javascript-enabled browser and HTTP... FWIW, deploying a CherryPy application is really trivial. I have not tested Divmod/nevow yet, but I think you should have a look there too. > |> - and no I don't want a web server > | > |If you don't want Apache, there are Python-based application servers. > |CherryPy comes to mind. > | > |> and php > | > |Why PHP ? > | > > seems popular Yes, but why PHP ? Python is quite good for web apps. > |> and browsers and Java > | > |Why Java ? > | > > it addresses what I want - to dynamically and securely download bits of code and > execute them on the remote machine... If you really want security, you have to keep the critical parts on the server. > |> and html or xml... - I want to write something that works > |> simply and reliably > | > |We do write SQL-based web apps all day long, and I can tell you they are > |certainly more simple and reliable than whatever eval()-based home-made > |solution we could imagine !-) > > Aah! but I would like you to stretch that imagination - to tell me how to do > some of what Java was designed to do, Initially, Java - it was named Oak by the time - was designed for embedded programming. It happened to be a failure. Then it was renamed to Java and "redesigned" (hum) for rich web client (applets). It still failed there. It also failed for traditional cross-platform GUI programming (too heavy and too autistic), and finally happened to make it on the web server side, but even there it's a really heavy-weight solution with no obvious practical advantage wrt/ more agile solutions (PHP, Python, Ruby, Perl etc) IMHO. > but better and easier, because this is > python we are talking about... indeed !-) > I saw something in another thread here - they were talking about weave ??? > - can I > use that if eval is nfg? Can't tell... > If my original post was unclear I am sorry - the point I want answered, if > possible, is how to make the client code effectively updateable on the fly - > because the answer to this will influence the whole design of the rest of the > system... This is something I have been thinking about... IMHO what you want is not to "update client code on the fly", but to make the client mostly a kind of interpreter for what the server sends in. That is, the client code itself doesn't contain any application logic, it gets it from the server and execute it. This can certainly be done with Pyro. Now while this may be an interesting project, I'm not really sure it's worth the effort when we already have HTTP, HTML and AJAX... -- bruno desthuilliers python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for p in 'onurb(a)xiludom.gro'.split('@')])"

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