Re: is python Object oriented??
On Feb 2, 4:10 am, Stephen Hansen wrote: > Anyway, it doesn't matter. We're losing the point here. The point is > that language support for private access, by disallowing user access > to private data, provides an unambiguous information hiding mechanism > which encourages encapsulation. Python's approach, however, which is > only a naming convention rather than a language feature, merely TRUSTS > the programmer not to break encapsulation. And sure, if we're all good > programmers, everything will go well and we'll end up with an > organized application. But the danger is still there: at any given > time, we COULD break encapsulation! > > > I was long-winded the last time I responded to this point so no one probably > read it :) Yes, we read it. You made good points!! Cheers, Hung -- http://mail.python.org/mailman/listinfo/python-list
Re: is python Object oriented??
On Fri, Jan 30, 2009 at 5:15 PM, Chris Rebert wrote: > On Thu, Jan 29, 2009 at 9:56 PM, Hung Vo wrote: > > > I'm new to Python and also wondering about OOP in Python. > > > > I want to justify the above question (is Python Object-Oriented?). > > Does Python follow the concepts/practices of Encapsulation, > > Polymorphism and Interface, which are quite familiar to Java > > programmers? > > If you're looking for a benchmark for object-orientedness, Smalltalk, > not Java, is the canonical language to compare against. I was introduced to OOP via C++/Java, so its quite nature to compare and contrast with the languages you know even they seem not to be original. I definitely will learn about Smalltalk. > > Anyway, to your three-pronged question: > - Yes, Python supports polymorphism. I find it hard to think of an > example of an OO language that doesn't. > > - Python does not support interfaces in the Java sense (although there > are a few third-party libraries that add such support); neither does > Smalltalk. Instead, both Smalltalk and Python use duck-typing to > similar effect. See http://en.wikipedia.org/wiki/Duck_typing Its seem to me that duck typing is a special case of static vs dynamic type debate and clearly Python is a dynamic type philoshopy's follower. > > - Python supports encapsulation. Prefixing an attribute/method with an > underscore indicates that other programmers should treat it as > 'private'. However, unlike B&D languages, Python itself does nothing > to enforce this privacy, leaving it instead to the good judgement of > the programmer, under the philosophy that "We're all consenting adults > here". This allows people to meddle with internals, at their own risk, > if it ends up being absolutely necessary. The enforcement point is > largely academic anyway, as most languages' reflection APIs let you > poke at ostensibly "private" things. I like the flexibility of not being enforced to the encapsulation rules, however, you're right, we do at our own risk and have to tradeoff the flexibility with the secure a static type system like Java provides. P.S. You appear to have posted the same message 3 times(!), which is a > bit annoying for readers. sorry for this annoyance. I dont know why a new post was made whenever i cliked on the topic link. Probably, there's something wrong with google group. on investigating... > > -- > Follow the path of the Iguana... > http://rebertia.com > -- http://mail.python.org/mailman/listinfo/python-list
Re: is python Object oriented??
On Jan 30, 4:19 am, Michael Torrie wrote: > M Kumar wrote: > > but still I am not clear of the execution of the code, when we write or > > execute a piece of python code without defining class, predefined class > > attributes are available (not all but __name__ and __doc__ are available). > > does it mean anything to this topic. Is it necessory to have __module__, > > __dict__ and __bases__ for a class object in python? > > I think you're confused as to what object-oriented means. OO defines > the internals of a language more than a particular programming paradigm. > Obviously python lets you program in a variety of paradigms, including > procedural and event-driven, but it is all very much object-oriented. > So ignore those that say python doesn't force you to use OOP, when in > fact it's unavoidable. It's just that you're not forced to place all > your code in class definitions. You don't need to because your code is > already object-oriented in that you're manipulating objects and their > attributes. > > As others have said, Python is an object-oriented language through and > through, closer to Smalltalk in many ways, the grand-daddy of all OO > languages. > > It appears that you are only really familiar with Java, and that leads > to a number of interesting misconceptions about OO. Java's bizarre OO > requires everything to be in a class, which leads many people to believe > this is what OO should be. In fact Java is a bit odd when it comes to > OO, as there are many things in Java that aren't in fact objects. For > example, primitives are intrinsic types and are not objects. > Furthermore class definitions are not objects either, at least from the > programmer's pov. You can't manipulate them by standard means as you > can in Smalltalk and Python. In Smalltalk and Python a "class" is an > object just as much as an instance of a class is an object which has a > constructor factory method that returns instance objects. Java also has > very strange ways of doing singleton patterns. You have to wrap > singletons in class and define them as "static." I think this was > inherited from C++. > > The most basic object in a python script is the module object which > represents the namespace of the current script. In effect a module > object is a singleton. It has a few attributes, and you can use it to > look up any of the objects it contains, such as functions, objects > (so-called variables), classes, etc. Everything in python is an object. > The statement: > > a = 4 > > defines an integer object "4" and binds a name to it, 'a.' You can even > check to see what methods the object supports by doing: > > >>> dir(4) > > ['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', > '__delattr__', '__div__', '__divmod__', '__doc__', '__float__', > '__floordiv__', '__getattribute__', '__getnewargs__', '__hash__', > '__hex__', '__index__', '__init__', '__int__', '__invert__', '__long__', > '__lshift__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', > '__oct__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', > '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', > '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', > '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', > '__rxor__', '__setattr__', '__str__', '__sub__', '__truediv__', '__xor__'] > > dir(a) would return the same thing. As you can see, all the operators > that can be performed with a number object are defined. This little > exercise alone should show you how much more object-oriented Python is > than Java. > > Python's OO capabilities are really exposed when you start extending > built-in types, or doing meta programming where you dynamically alter > classes (and instance objects) on the fly. I'm new to Python and also wondering about OOP in Python. I want to justify the above question (is Python Object-Oriented?). Does Python follow the concepts/practices of Encapsulation, Polymorphism and Interface, which are quite familiar to Java programmers? Cheers, Hung -- http://mail.python.org/mailman/listinfo/python-list
Re: is python Object oriented??
On Jan 30, 4:19 am, Michael Torrie wrote: > M Kumar wrote: > > but still I am not clear of the execution of the code, when we write or > > execute a piece of python code without defining class, predefined class > > attributes are available (not all but __name__ and __doc__ are available). > > does it mean anything to this topic. Is it necessory to have __module__, > > __dict__ and __bases__ for a class object in python? > > I think you're confused as to what object-oriented means. OO defines > the internals of a language more than a particular programming paradigm. > Obviously python lets you program in a variety of paradigms, including > procedural and event-driven, but it is all very much object-oriented. > So ignore those that say python doesn't force you to use OOP, when in > fact it's unavoidable. It's just that you're not forced to place all > your code in class definitions. You don't need to because your code is > already object-oriented in that you're manipulating objects and their > attributes. > > As others have said, Python is an object-oriented language through and > through, closer to Smalltalk in many ways, the grand-daddy of all OO > languages. > > It appears that you are only really familiar with Java, and that leads > to a number of interesting misconceptions about OO. Java's bizarre OO > requires everything to be in a class, which leads many people to believe > this is what OO should be. In fact Java is a bit odd when it comes to > OO, as there are many things in Java that aren't in fact objects. For > example, primitives are intrinsic types and are not objects. > Furthermore class definitions are not objects either, at least from the > programmer's pov. You can't manipulate them by standard means as you > can in Smalltalk and Python. In Smalltalk and Python a "class" is an > object just as much as an instance of a class is an object which has a > constructor factory method that returns instance objects. Java also has > very strange ways of doing singleton patterns. You have to wrap > singletons in class and define them as "static." I think this was > inherited from C++. > > The most basic object in a python script is the module object which > represents the namespace of the current script. In effect a module > object is a singleton. It has a few attributes, and you can use it to > look up any of the objects it contains, such as functions, objects > (so-called variables), classes, etc. Everything in python is an object. > The statement: > > a = 4 > > defines an integer object "4" and binds a name to it, 'a.' You can even > check to see what methods the object supports by doing: > > >>> dir(4) > > ['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', > '__delattr__', '__div__', '__divmod__', '__doc__', '__float__', > '__floordiv__', '__getattribute__', '__getnewargs__', '__hash__', > '__hex__', '__index__', '__init__', '__int__', '__invert__', '__long__', > '__lshift__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', > '__oct__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', > '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', > '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', > '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', > '__rxor__', '__setattr__', '__str__', '__sub__', '__truediv__', '__xor__'] > > dir(a) would return the same thing. As you can see, all the operators > that can be performed with a number object are defined. This little > exercise alone should show you how much more object-oriented Python is > than Java. > > Python's OO capabilities are really exposed when you start extending > built-in types, or doing meta programming where you dynamically alter > classes (and instance objects) on the fly. I'm new to Python and also wondering about OOP in Python. I want to justify the above question (is Python Object-Oriented?). Does Python follow the concepts/practices of Encapsulation, Polymorphism and Interface, which are quite familiar to Java programmers? Cheers, Hung -- http://mail.python.org/mailman/listinfo/python-list
Re: is python Object oriented??
On Jan 30, 4:19 am, Michael Torrie wrote: > M Kumar wrote: > > but still I am not clear of the execution of the code, when we write or > > execute a piece of python code without defining class, predefined class > > attributes are available (not all but __name__ and __doc__ are available). > > does it mean anything to this topic. Is it necessory to have __module__, > > __dict__ and __bases__ for a class object in python? > > I think you're confused as to what object-oriented means. OO defines > the internals of a language more than a particular programming paradigm. > Obviously python lets you program in a variety of paradigms, including > procedural and event-driven, but it is all very much object-oriented. > So ignore those that say python doesn't force you to use OOP, when in > fact it's unavoidable. It's just that you're not forced to place all > your code in class definitions. You don't need to because your code is > already object-oriented in that you're manipulating objects and their > attributes. > > As others have said, Python is an object-oriented language through and > through, closer to Smalltalk in many ways, the grand-daddy of all OO > languages. > > It appears that you are only really familiar with Java, and that leads > to a number of interesting misconceptions about OO. Java's bizarre OO > requires everything to be in a class, which leads many people to believe > this is what OO should be. In fact Java is a bit odd when it comes to > OO, as there are many things in Java that aren't in fact objects. For > example, primitives are intrinsic types and are not objects. > Furthermore class definitions are not objects either, at least from the > programmer's pov. You can't manipulate them by standard means as you > can in Smalltalk and Python. In Smalltalk and Python a "class" is an > object just as much as an instance of a class is an object which has a > constructor factory method that returns instance objects. Java also has > very strange ways of doing singleton patterns. You have to wrap > singletons in class and define them as "static." I think this was > inherited from C++. > > The most basic object in a python script is the module object which > represents the namespace of the current script. In effect a module > object is a singleton. It has a few attributes, and you can use it to > look up any of the objects it contains, such as functions, objects > (so-called variables), classes, etc. Everything in python is an object. > The statement: > > a = 4 > > defines an integer object "4" and binds a name to it, 'a.' You can even > check to see what methods the object supports by doing: > > >>> dir(4) > > ['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', > '__delattr__', '__div__', '__divmod__', '__doc__', '__float__', > '__floordiv__', '__getattribute__', '__getnewargs__', '__hash__', > '__hex__', '__index__', '__init__', '__int__', '__invert__', '__long__', > '__lshift__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', > '__oct__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', > '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', > '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', > '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', > '__rxor__', '__setattr__', '__str__', '__sub__', '__truediv__', '__xor__'] > > dir(a) would return the same thing. As you can see, all the operators > that can be performed with a number object are defined. This little > exercise alone should show you how much more object-oriented Python is > than Java. > > Python's OO capabilities are really exposed when you start extending > built-in types, or doing meta programming where you dynamically alter > classes (and instance objects) on the fly. I'm new to Python and also wondering about OOP in Python. I want to justify the above question (is Python Object-Oriented?). Does Python follow the concepts/practices of Encapsulation, Polymorphism and Interface, which are quite familiar to Java programmers? Cheers, Hung -- http://mail.python.org/mailman/listinfo/python-list
Re: How to read all files in a directory
Hello Larry, Thanks a lot for your response. It helps me a lot. I used your suggestion and got an error: path=r'C:\datafiles\' ^SyntaxError: EOL while scanning single-quoted string Then, I changed just a little bit and it works fine. I set path='C:\\datafiles\\' instead of path=r'C:\datafiles\' Again Larry, I appreciate your suggestion Hung Vo.Larry Bates <[EMAIL PROTECTED]> wrote: Not tested:import globimport ospath=r'C:\datafiles\'for fileName in glob.glob(os.path.join(path,'*.DAT')):dataFile=open(fileName, 'r').readlines().. Continue yur code here.-Larry Bateshungbichvo wrote:> Dear All,> > My python application is small. It reads data from a file.> My code is:> fileName = '900128.DAT'> dataFile = open(fileName, 'r').readlines()> I have to run 100 input files .DAT. Each time I run application, I have > to change code fileName to a new one. For example, fileName > = 'NewFile.DAT'.> I do not know how I can process all file with extension .DAT in a > specific directory once only.> > Any suggestion will be appreciated,> > Thank you.> > > Yahoo! FareChase - Search multiple travel sites in one click. -- http://mail.python.org/mailman/listinfo/python-list
