mai date ma in morti mati cu masurile tale de handicapat --- On Tue, 1/18/11, tutor-requ...@python.org <tutor-requ...@python.org> wrote:
From: tutor-requ...@python.org <tutor-requ...@python.org> Subject: Tutor Digest, Vol 83, Issue 74 To: tutor@python.org Date: Tuesday, January 18, 2011, 10:32 AM Send Tutor mailing list submissions to tutor@python.org To subscribe or unsubscribe via the World Wide Web, visit http://mail.python.org/mailman/listinfo/tutor or, via email, send a message with subject or body 'help' to tutor-requ...@python.org You can reach the person managing the list at tutor-ow...@python.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Tutor digest..." Today's Topics: 1. Re: Why super does not work ! (Steven D'Aprano) 2. Re: Why super does not work ! (Alan G) 3. Re: Why super does not work ! (Karim) 4. Re: Exactly duplicating strftime behavior? (Izz ad-Din Ruhulessin) 5. How to plot graph? (tee chwee liong) ---------------------------------------------------------------------- Message: 1 Date: Tue, 18 Jan 2011 10:09:35 +1100 From: Steven D'Aprano <st...@pearwood.info> To: python mail list <tutor@python.org> Subject: Re: [Tutor] Why super does not work ! Message-ID: <4d34cc2f.1010...@pearwood.info> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Karim wrote: > > > Hello, > > I implemented Observer DP on a listbox (Tkinter) as follows and I don't > understand why super() is not working and Observable.__init__(self) is > working, cf below: You seem to be confused about your class design. On the one hand, you inherit from Listbox, but then you *also* use composition and/or delegation on a Listbox instance: class ListObservable(Listbox, Observable): def __init__(self): [...] self.liste = Listbox(listvariable=self.listeContenu, selectmode='single') That means that a ListObservable instance both *is* a Listbox and *contains* a Listbox at the same time. I'm not saying this is necessarily wrong, but it is unusual, and confuses the model. At the very least, you need to document why you have done this. > class ListObservable(Listbox, Observable): > """Creation de widget Listbox""" > def __init__(self): > super(ListObservable, self).__init__() > #Observable.__init__(self) Are both Listbox and Observable documented as suitable for multiple inheritance? My guess is that Listbox is not, and I can see from your source code that Observable is *not* suitable for multiple inheritance. If Listbox is documented as suitable for multiple inheritance, then it is a bug in Listbox. If it is not, then it is a bug in your code, by using it for multiple inheritance. Multiple inheritance in Python is cooperative, not enforced, and it is tricky to get right and is *very* sensitive to any class which fails to cooperate. Thousands and thousands of words have been written on the perils and difficulties of multiple inheritance, particularly by Michele Simionato who I consider to be THE authority on MI in Python. Some of the most important articles are: Michele Simionato: Things to Know About Python Super http://www.artima.com/weblogs/viewpost.jsp?thread=236275 http://www.artima.com/weblogs/viewpost.jsp?thread=236278 http://www.artima.com/weblogs/viewpost.jsp?thread=237121 Mixins considered harmful: http://www.artima.com/weblogs/viewpost.jsp?thread=246341 http://www.artima.com/weblogs/viewpost.jsp?thread=246483 http://www.artima.com/weblogs/viewpost.jsp?thread=254367 http://www.artima.com/weblogs/viewpost.jsp?thread=254507 Generic functions vs mixins: http://www.artima.com/weblogs/viewpost.jsp?thread=237764 Straits: http://www.artima.com/weblogs/viewpost.jsp?thread=246488 James Knight: Python's Super Considered Harmful http://fuhm.net/super-harmful/ Summary: this is *not* a bug in super. It's really a side-effect of the fact that multiple inheritance itself is often the wrong thing to use, and even when it is right, it is often tricky to get it right. To put it another way: don't use multiple inheritance unless you have to, there are better ways, such as by composition. -- Steven ------------------------------ Message: 2 Date: Tue, 18 Jan 2011 01:32:39 +0000 (UTC) From: Alan G <alan.ga...@btinternet.com> To: tutor@python.org Subject: Re: [Tutor] Why super does not work ! Message-ID: <loom.20110118t022639-...@post.gmane.org> Content-Type: text/plain; charset=us-ascii Steven D'Aprano <steve <at> pearwood.info> writes: > fact that multiple inheritance itself is often the wrong thing to use, > and even when it is right, it is often tricky to get it right. To put it > another way: don't use multiple inheritance unless you have to, there > are better ways, such as by composition. Or use a language where MI is the normal and idiomatic way to do things because the language assumes it and so it just works. There are very few such languages but Lisp is one :-) Sadly Python isn't, and when using MI I always avoid super() Which is a huge shame since MI is where super() should be most useful... But in my experience MI in Python is definitely a place where explicit is better than implicit. Alan G. ------------------------------ Message: 3 Date: Tue, 18 Jan 2011 07:31:10 +0100 From: Karim <karim.liat...@free.fr> Cc: tutor@python.org Subject: Re: [Tutor] Why super does not work ! Message-ID: <4d3533ae.4050...@free.fr> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Thanks Izz, Luke, Steven and Alan! That's I figured out with MI and super. Steven I understand the point to have Listbox contains a Listbox. Before the code was in App class and I extracted it to do an outside class making the mistake. But magic of Python it's working (but I know it's awful). The code is working but I am not totally happy because of many EntryObserver almost identical objects (except from update and grid() options) Is it possible to simplify this structure? Regards Karim The rest of the code is below: #!/usr/bin/env python2.7 """Module ObserverGraphique.py Une implementation du design pattern Observer. """ from Tkinter import * from observable import Observable from observer import AbstractObserver data_base = { 'Employe1': ['Joel', 'Durant', '0623'], 'Employe2': ['Marc', 'Donce', '0624'], 'Employe3': ['George', 'Roux', '0625'], 'Employe4': ['Alain', 'Richard', '0626'] } __all__ = ['App', 'ListObservable', 'Entry1Observer', 'Entry2Observer', 'Entry3Observer'] class App(Frame): """Application graphique avec Tkinter implementant un Observer Design Pattern.""" def __init__(self, master=None): Frame.__init__(self, master) self.master.title("Exemple : Observer Design Pattern") self.grid() self.createLabels() self.createObservable() self.createObservers() self.registerObservers() def createLabels(self): """Creation de widgets Label""" self.label1 = Label(text="Nom :") self.label2 = Label(text="Prenom :") self.label3 = Label(text="Poste :") self.label1.grid(row=1, column=1, sticky=W) self.label2.grid(row=2, column=1, sticky=W) self.label3.grid(row=3, column=1, sticky=W) def createObservable(self): """Creation de la listBox observable.""" self.sujet = ListObservable() def createObservers(self): """Creation des champs d'entre texte observateurs de la liste.""" self.nom = Entry1Observer(self.sujet) self.prenom = Entry2Observer(self.sujet) self.poste = Entry3Observer(self.sujet) def registerObservers(self): """Enregistrement des observateurs.""" self.sujet.attach(self.nom) self.sujet.attach(self.prenom) self.sujet.attach(self.poste) class ListObservable(Listbox, Observable): """Creation de widget Listbox""" def __init__(self): #super(ListObservable, self).__init__() Observable.__init__(self) self._value = None self.listeContenu = StringVar() self.listeContenu.set(' '.join(sorted(data_base.keys()))) self.liste = Listbox(listvariable=self.listeContenu, selectmode='single') self.liste.grid(row=0, column=1, sticky=N+S+W) self.liste.bind('<Double-1>', self.onSelect) self.liste.selection_set(0) def onSelect(self, e): if not self.liste.curselection(): self.setValue(0) else: self.setValue(self.liste.get(self.liste.curselection())) self.notify() def setValue(self, select): self._value = select def getValue(self): return self._value class Entry1Observer(Entry, AbstractObserver): """Creation de widget Entry 1""" def __init__(self, sujet=None): #super(Entry1Observer, self).__init__(sujet) AbstractObserver.__init__(self, sujet) self.text = StringVar() self.entry = Entry(textvariable=self.text) self.entry.grid(row=1, column=2) def update(self): a = self.sujet.getValue() self.text.set(data_base[a][1]) print a class Entry2Observer(Entry, AbstractObserver): """Creation de widget Entry 2""" def __init__(self, sujet=None): AbstractObserver.__init__(self, sujet) self.text = StringVar() self.entry = Entry(textvariable=self.text) self.entry.grid(row=2, column=2) def update(self): a = self.sujet.getValue() self.text.set(data_base[a][0]) class Entry3Observer(Entry, AbstractObserver): """Creation de widget Entry""" def __init__(self, sujet=None): AbstractObserver.__init__(self, sujet) self.text = StringVar() self.entry = Entry(textvariable=self.text) self.entry.grid(row=3, column=2) def update(self): a = self.sujet.getValue() self.text.set(data_base[a][2]) if __name__ == '__main__': app=App() app.mainloop() # ----- end of file ----- # class AbstractObserver(object): """Interface general des observateurs""" def __init__(self, sujet): """Constructeur""" self.sujet = sujet def update(self): """Methode a implementer par les observateurs""" pass On 01/18/2011 02:32 AM, Alan G wrote: > Steven D'Aprano<steve<at> pearwood.info> writes: > >> fact that multiple inheritance itself is often the wrong thing to use, >> and even when it is right, it is often tricky to get it right. To put it >> another way: don't use multiple inheritance unless you have to, there >> are better ways, such as by composition. > Or use a language where MI is the normal and idiomatic way > to do things because the language assumes it and so it just > works. There are very few such languages but Lisp is one :-) > > Sadly Python isn't, and when using MI I always avoid super() > Which is a huge shame since MI is where super() should > be most useful... But in my experience MI in Python is > definitely a place where explicit is better than implicit. > > Alan G. > > > > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor ------------------------------ Message: 4 Date: Tue, 18 Jan 2011 07:35:30 +0100 From: Izz ad-Din Ruhulessin <izzaddin.ruhules...@gmail.com> To: Hugo Arts <hugo.yo...@gmail.com> Cc: tutor@python.org Subject: Re: [Tutor] Exactly duplicating strftime behavior? Message-ID: <AANLkTin-GdXd0rfupKHa=-RN+6d_ywYawDrv2Nsw=m...@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Hi Hugo, Problem solved, thanks! Kind regards, Izz ad-Din 2011/1/17 Hugo Arts <hugo.yo...@gmail.com> > On Mon, Jan 17, 2011 at 8:29 PM, Izz ad-Din Ruhulessin > <izzaddin.ruhules...@gmail.com> wrote: > > Hi all, > > I'm designing a module which aims to provide full compatibility with > > Pythons' datetime module. > > However, I can't find out how some operators in strftime function, > namely: > > those who use the locale. (%a, %A, %b, etc.) > > How do I access this locale and it's values? > > Thanks in advance. > > Kind regards, > > Izz ad-Din > > Check out the locale module: > > http://docs.python.org/library/locale.html#locale.nl_langinfo > > HTH, > Hugo > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/tutor/attachments/20110118/522e990e/attachment-0001.html> ------------------------------ Message: 5 Date: Tue, 18 Jan 2011 10:30:53 +0000 From: tee chwee liong <tc...@hotmail.com> To: <tutor@python.org> Subject: [Tutor] How to plot graph? Message-ID: <bay156-w28c9e6f96071b97a33cdfeb5...@phx.gbl> Content-Type: text/plain; charset="iso-8859-1" hi all, i'm new to python and this is advanced for me. is there a way to plot data with python? i want to plot EyVt, EyHt on the Y-axis and Lane on the X-axis as attached or below. currently i'm using Python2.5 and Win XP. thanks a lot. Eg: Platform: PC Tempt : 25 TAP0 :0 TAP1 :1 +++++++++++++++++++++++++++++++++++++++++++++ Port Chnl Lane EyVt EyHt +++++++++++++++++++++++++++++++++++++++++++++ 0 1 1 75 55 0 1 2 10 35 0 1 3 25 35 0 1 4 35 25 0 1 5 10 20 +++++++++++++++++++++++++++++++++++++++++++++ Time: 20s -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/tutor/attachments/20110118/80b250af/attachment.html> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... 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