Learning Python, 2nd Edition 322
Learning Python 2nd Edition | |
author | Mark Lutz & David Ascher |
pages | 591 |
publisher | O'Reilly & Associates, Inc. |
rating | 10 |
reviewer | Ursus Maximus |
ISBN | 0596002815 |
summary | An introduction to Python programming |
Python is a dynamic, interpreted, object oriented language used for both scripting and systems programming. Python is known for being easy to learn and use, while also being powerful enough to be used for such projects as Zope and the Chandler project. Its growing popularity is also based on its reputation for fostering programmer productivity and program maintainability. One drawback sometime cited is its relatively slow execution speed compared to compiled languages such as C.
For myself, I have probably read too many books about Python, but that is because I am an amateur hacker who learns programming slowly, and I find that reading several books about the same topic, covering the subject matter from different angles, allows me to better absorb the material. For me, this was a good review of the core language and a welcome refresher course on the newer aspects introduced in versions 2.2 and 2.3. For anyone who is new to Python and wants to learn from the ground up, this book would be a great place to start.
Mark Lutz is an authority on Python and one if its leading teachers, with both Learning and O'Reilly's Programming Python to his credit, as well as the courses and seminars he teaches professionally. In updating the original version, which was already very good, Mark has polished the chapters on the core language to a nearly perfect level, while his co-author David Ascher has done the same on the more advanced aspects of the book. In addition, Mr Lutz has benefited from extensive feedback from students and readers, and his explanations therefore anticipate common misunderstandings. Each chapter is accompanied by a problem and exercise section and answers are included at the back of the book.
A major addition to the new edition is a chapter on "Advanced Function Topics," including list comprehensions, generators and iterators. Python is sometimes used with a functional programing style almost similar to Lisp, although to List purists that may sound like heresy. The recent versions of the language have significantly upgraded Python's support for the functional style. Functions cover three chapters in the 2nd edition instead of just one.
Another major change since the first edition is extended coverage of Modules, which now occupies four chapter instead of just one. Python modules are a high level package structure for code and data, and they help facilitate code reuse. Yet another addition is coverage of Python's "new style classes." Coverage of classes and object oriented programming has been greatly expanded and now includes five whole chapters and almost 100 pages. Coverage of exceptions now is expanded to three chapters.
If you have been considering learning Python, now would be a great time since this new book is the perfect introductory text. If you already know Python and have read the first edition of Learning Python or another introductory text, then this book may not be essential since the new language features are covered pretty well on the web in various places, and you might be better advised to read one of the other fine books on non-introductory aspects of Python. But this book is about as good an introduction to the language as you are likely to find. The book does not cover all of the Python libraries nor many other topics, but it does briefly touch on the major libraries, frameworks, gui toolkits, and community resources.
If you want to learn the core Python language quickly, this may be your best bet. Learning Python only covers the basics, but it is deep in information on what it does cover. Well written, understandable, and in a very logical arrangement, this book is densely packed with info.
I have often found myself returning to the original book, and the new book will now fill this role. It is deep in information, well written, and a joy to read. For an experienced programmer who is just learning Python, it may be possible to thoroughly learn everything about the core language in one reading of this book. For relative newbies, it will be an often-used resource.
To read more reviews of books about Python, visit the Python Learning Foundation. You can purchase the Learning Python, 2nd Ed. from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
A nice comparison of Python with other languages.. (Score:5, Informative)
I prefer Ruby [rubyforge.org], but there seem to be a lot of healthy discussions of various language features and ideas across the scripting language community. The "Python comparison page", for example, has a link to John Ousterhout's paper on why scripting languages are useful - even thought he wrote the paper about Tcl, it's just as applicable to Python or Ruby.
Re:A nice comparison of Python with other language (Score:3, Informative)
I've used python for several years, but only 2 weeks after stumbling across "Programming Ruby" (Available free at http://www.rubycentral.com/book/ [rubycentral.com]), I've switched all new development to Ruby. As a language, it just clicks for me. It's like the best of all possible worlds. It brings in the cleanliness of Python (without the whitespace issues, for those who dislike that), the hack value of Perl (tightly integated regex, etc), the OO of smalltalk/java (for those that like that kind of thing)
Re:A nice comparison of Python with other language (Score:2)
adict = {'key': 'val', 'key2': 'val2', 'key3': 3.14}
for key in adict:
print 'k -> ', adict[key]
Re:A nice comparison of Python with other language (Score:2)
make that last line:
print '%s -> %s' % (key, adict[key])
Re:A nice comparison of Python with other language (Score:5, Insightful)
1) I prefer the Python example. It's easier to read. And easier to write the first time. That's the reason Python is better than Ruby: when you write code, you get it right the first time more often. And that's such a huge advantage.
Of course, you screwed up. (I assume you wanted to print the value of k rather than the letter k)
2) You used a comprehension in Ruby but not in Python. And adict.items() would have been easier than adict.keys()
To be more fair:
adict = {'key':'val','key2':'val2','key3':3.14}
[sys.stdout.write(k+'-> '+str(v)+'\n') for k,v in adict.items()]
But if I was writing the code, I'd use a for loop rather than a comprehension.
But for penis length competitions, we'll use the latter.
Bryan
Re:A nice comparison of Python with other language (Score:2)
My rule of thumb: if I don't need the results of a list comprehension, it's probably best written as a regular for loop. The fact that the original poster used 'sys.stdout.write' when he wanted to print something is a dead-giveaway (print is a statement, which is why it's not valid in the list comp):
This:
[sys.stdout.write(k+'-> '+str(v)+'\n') for k,v in adict.items()]
Could have just as easily been written (more clearly) a
Re:A nice comparison of Python with other language (Score:2)
[print k+' -> '+v for k,v in adict.items()]
Re:A nice comparison of Python with other language (Score:2)
The comprehension doesn't add anything to this example. Let's stick with the time-honored:
for k, v in adict.items():
print k+'->'+v
(you can put it on one line if you really want)
Re:A nice comparison of Python with other language (Score:2)
for k, v in adict.iteritems():
print k, '->', v
I think this is actually more readable than Ruby's "each" function which is a weaker alternative to iteration.
Re:A nice comparison of Python with other language (Score:3, Interesting)
It generates a graphical waveform from the component harmonics, as well as graphing the first 10 harmonics.
Source Code: http://tylere.com/waveform.rb.txt [tylere.com]
Some Examples:
Square Wave [tylere.com]
A Phased Sine Wave [tylere.com]
Triangular Wave [tylere.com]
Sawtooth Wave [tylere.com]
Re: (Score:2, Informative)
Re:A nice comparison of Python with other language (Score:3, Informative)
Virtual +1 insightful to you (Score:3, Insightful)
Your "Python stole the thunder" analysis is not quite right, though, and it relates to why I prefer Python.
Ruby is as old as Python, but Matz wrote Ruby to do his own Japanese *nix work. He focused on his own needs, but made it available to all, so essentially he was focusing on the Japanese *nix community and their needs. The Japanese *nix community, for example, cares far more about handling legacy Japanese data than about handl
Lisp vs Python comparison (Score:4, Informative)
Python? (Score:5, Informative)
Open source, expressive (very short code can achieve a lot), readable (very short expressive code is easily groked -- fewer bugs), no direct pointer manipulation (safe -- fewer bugs), integrates nicely with other languages, runs on a variety of platforms, very easy to learn.
I, too would recommend learning python. It is a very good, language. Zeolotry is another thing though. Keep your mind open. Learn all the languages you can. This book, I can't comment, although I received it a week ago I haven't gotten around to reading it yet.
Re:Python? (Score:5, Interesting)
The importance and utility of this can't be overstated. Python absolutely rocks as a rapid development environment. I have not personally experienced a language that lets me go from concept to implementation nearly so quickly. Once an application is up and running, Python provides a great toolset for profiling your project and making it easy to replace performance-critical sections with the low-level language of your choice.
Does your crypto application need a faster random generator? Replace parts of that module with C. The rest of your project still gets the benefits of a strongly typed, object-oriented language with a robust library of string manipulation, pattern matching, and GUI interfacing functions.
It really is a project manager's dream come true. Python has replaced Perl as my language of choice for all new development.
Re:So, ... (Score:2)
Re:Python? (Score:2)
No. Learn all the languages that will make you a better programmer. Learn languages that will expand your understanding of software engineering. Learn languages that will make you more productive. But for goodness' sake, don't waste your time learning every language you run across: the vast majority of languages are simply unproductive compared to a small handful of better, higher-quality languages.
Languages can be compared based on objective criteria. You can honestl
Re:Python? (Score:2, Interesting)
What I'm kinda curious about is whether they use mod_python. From the looks of the URL's on Adsense and AdWords it seems likely that they are using the Publisher handler, but I've never heard any official (or even rumor) about it.
Re:Python? (Score:3, Informative)
One of the best examples of this is Jython - python implemented in 100% java. This allows the flexibility of a scripting language with the security and portability of Java.
1st edition (Score:4, Informative)
Maybe its just me though.
Re:1st edition = PAPERWEIGHT (Score:4, Interesting)
Anyway. I immediately ran off to the nearest bookstore and grabbed the first edition of the book. I read it once through and it--along with a lot of googling--helped me understand what I was doing, but once I had gone through it once I couldn't use it to recall the details of what I had been taught. If I wanted to look up something that I knew I had learned *from the book* I would have to look it up *on the web* (e.g. syntax or the required parameters of a function) because the index was useless. I never found anything I needed from that book once I did the initial once-through reading.
Though let's not gloss over the fact that I obviously learned python fairly well from this book because I did get the job! So sure, if you need to learn the language, the first edition did the job, but you'd better buy a *real* python book while you're there at the bookstore because as soon as you were done with Learning... it was nothing more than a paperweight.
Re:1st edition = PAPERWEIGHT (Score:2)
Re:1st edition = PAPERWEIGHT (Score:2)
on par with TCL except for C (Score:3, Interesting)
While TCL remains my personal favorite, Python is really good, except for the creating-your-own-extensions part. The Python's C API needs a lot of catching up to do to match the excellence of TCL's.
Re:on par with TCL except for C (Score:4, Informative)
It uses C++ and lots of template mojo, but you don't really need to understand all that to use it.
Python is amazing (Score:5, Informative)
This is not a religious argument; I'm not advocating that python is the one language you should use or anything like that. In fact, not having an "ideology" is one of python's major strengths.
If you're asking "why python [linuxjournal.com]", ESR has said it better than I ever could.
I'm yet another of those who experienced extremely small turnaround times for python programs. It took me a week, working part time (I estimate about 30 hours) totally, to release 1.0 of gretools [ernet.in], starting from scratch. I had not written a single line of python code before that, mind you.
Why python is great:
Its not a religion. It doesn't force its style of thinking on you. Functional programming, excellent string manipulation tools, classes, inheritance, exceptions, polymorphism, operating system integration, they're all available. This is python's biggest advantage. Whichever background you're coming from, you can very quickly become effective at python.
Incredibly compact code. This is largely a consequence of the previous point. Apart from that it is dynamically typed, and has lots of other cool features. Like doing away with braces for delimiting blocks. People who know nothing about the language flame it for using indentation, but I have never found it confusing, and it makes the code smaller far more readable.
A user-friendly programming language! You aren't going to believe this until you've actually programmed in python. Its got this amazing property that if you can express a thought in constant space mentally, then you can code it in a constant number of lines, most of the time in a single line. In other words, the abstractions of the programming language match the "natural" abstractions of programmers very closely. After just a couple of days I got so used to this that I began to "predict" language features intuitively. At one point I just knew there had to be a language construct for something I was trying to do, and found that it was the reduce function.
Simple syntax. Python manages to have all these features while retaining a very simple syntax, perhaps even simpler than C. This is a big plus, because it gets out of the way and Does What You Mean.
Convinced? Get started now!
Re:Python is amazing (Score:2)
I agree with you overall, but Python does bow down to the temple of OOP. To me, a heavy OOP style of thinking feels very dated, even though Python has a very dynamic nature to its OOPness.
Re:Python is amazing (Score:2)
Of course, I don't know how "object oriented" is the same as "dated" in your head, so maybe it won't work for you.
Re:Python is amazing (Score:2)
Maybe I slept through too many CS classes and can't wrap my brain around OOP, maybe it's my failings as a coder, maybe I have a lot less free time nowadays than I used to, but I've been able to do a ton of useful work in Perl and haven't even been able to get started in Python.
Maybe I'll give it an 8th try one of these days. I feel like I'
Re:Python is amazing (Score:2)
Re:Python is amazing (Score:2)
Interesting point - most of the learning material is OOP-related, though, so I feel pretty lost trying to learn Python without knowing OOP. But that's good to know.
Re:Python is amazing (Score:5, Interesting)
I guess Perl is just traditionally what you do these things with. It's not necessarily better. Perl also doesn't support Windows directly like Python does - if you want Perl in Win32 you pretty much have to go with ActiveState whereas Python.org has a Win32 specific distribution. Then again, it's difficult to compete against CPAN's sheer size.
But anyway, it doesn't matter. We use what we want/like and it's cool that we have choices.
However, over the past year or so I've also been looking at Ruby. Not to get into a religious argument (as you say) over which language is better, but if you like Python you should take a look at Ruby. If you're a Windows user there's an installer [sourceforge.net] available, which comes with a full book (in CHM format) that can get you running in no time if you already know Python. As Perl and Python, Ruby has extensions and so on. I do like the OO features in Ruby a bit better than Python.
And least but not least, there's Lua. I wouldn't use Lua the same way I use Python, but Lua is a joy to embed, much more so than Python.
Ahhh, language wars. Cheers =)
Re:Python is amazing (Score:2)
What is wrong with Activestate? Activestate is Perl's "Win32 specific distributition". Don't really see the difference.
Re:Python is amazing (Score:2, Interesting)
There's nothing wrong with ActiveState, except that they lag behind the main *nix releases and are generally slow to incorporate fixes. It also ships with a bunch of stuff you might not necessarily want. For example, the COM extensions. The fact that I'm running in Windows doesn't necessarily mean I want to use COM. It also takes way too long to install, considering what it is.
The Win32
Python vs Java (Score:2)
Generally speaking, I liked Python quite a bit, especially the identation delimeting code blocks thing quite a bit, especially the visual cleanness of the code (although this was slightly offset by the need to dereference member variables with "this->"). I found the module system a bit squirrely, especially th
Re:Python is amazing (Score:2)
You mean they've fixed it so you don't have to rigidly adhere to Python's indentation conventions? 'Cause that and tab damage are the things that keep me from learning it.
I know what you mean. I've avoided C because of those damned curly braces. Give me good ol' "begin" and "end" blocks from Pascal - at least with those you know where you stand!
Upgrade? (Score:2)
If there's anything I hate, it's these big, thick, 1000-page (or 500-odd page) books which tell me how to use the Help system in Appendix 42.
So, I'm always wary.
O'Reilly & Python (Score:3, Informative)
For experienced programmers (Score:5, Insightful)
Free Python Books (Score:5, Informative)
Even if you do mind reading books on your computer screen, most of these books (actually I think all of them) are also available as physical printed books as well.
Thinking In Python [mindview.net] by Bruce Eckel
An Introduction to Python [network-theory.co.uk] by Guido van Rossum, and Fred L. Drake, Jr. (Editor)
How To Think Like a Computer Scientist: Learning with Python [greenteapress.com] by Allen Downey, Jeff Elkner and Chris Meyers
Dive Into Python: Python for Experienced Programmers [diveintopython.org] by Mark Pilgrim
Text Processing In Python [gnosis.cx] by David Mertz
Python Language Reference Manual [network-theory.co.uk] by Guido van Rossum
python runtime (Score:4, Insightful)
Re:python runtime (Score:2)
Oh well, don't drag Java into that. Especially concerning speed.
BTW, I'm not sure about python, someone please straighten this out - I bet it's similar, but Perl isn't "interpreted language" as such. It is some kind of hybrid: From user point of view it's interpreted, the program is its own source code etc. But from the system's point of view, it's compiled, only compilation takes place right before launching t
Re:python runtime (Score:3, Informative)
I love this setup. Your program will st
Re:python runtime (Score:2)
Yes, similar to a .java file.
A JIT-enabled JVM emits real machine code, IIRC.
Nope. The JVM executes bytecode. The JIT compiles the bytecode into native machine code and caches the results. Before a given block of code is executed, the JVM checks its cache to see if it's still stored, and if so, it executes the pre-compiled version.
Note that there's no strong reason (that I know of) why the Python VM couldn't also compile Python bytecode int
Re:python runtime (Score:2)
Re:python runtime (Score:2)
Second, by definition, a JIT compiler runs immediately before the bytecode in question is to be executed. A system that turned the bytecode into native machine code would just be a plain ol' compiler.
Third, Psyco [sourceforge.net] might come pretty close to what you want, except that it doesn't write out a compiled binary.
Re:python runtime (Score:2, Interesting)
Re:python runtime (Score:3, Interesting)
Re:python runtime (Score:4, Interesting)
Please don't confuse performance and size. Larger systems don't require bigger performance, performance is needed in tight inmost loops. And those you can implement in C while retaining the rest of the Python code.
actually... (Score:2, Interesting)
i think EVE proves that python is ready for big projects, even when performance is critical.
Re:python runtime (Score:2)
No, it is the tradeoff between efficient and less efficient implementations of a language. There are languages that usually come with rather fast implementations while being very dynamic and flexible, like Common Lisp, which is usually compiled to native code. (Of course, there are also completely crappy and inflexible languages that are slow a
Half Life (Score:2)
Re: (Score:2)
Test of a language (Score:5, Insightful)
def quicksort(list):
if len(list) > 1:
pivot = list[0]
left = [x for x in list if x < pivot]
right = [x for x in list if x > pivot]
pivot = [x for x in list if x == pivot]
return quicksort(left) + pivot + quicksort(right)
return list
I'd say this speaks for itself. Enjoy.
Re:Test of a language (Score:2)
Try:
def quicksort(list):
if len(list) > 1:
pivot = list[0]
left, middle, right = []. []. []
for item in list:
if item < pivot: left.append(item)
if item == pivot: middle.append(item)
if item > pivot: right.append(item)
return quicksort(left) + middle + quicksort(right)
else:
return list
The
left = middle = rig
Re:Test of a language (Score:2)
Yep. Another "failing" of this implementation (and yours, too) is that it doesn't do the sort in-place, so it uses n log n memory. The in-place sort implementation is what makes most really fast implementations so hairy and difficult to understand.
Re:Test of a language (Score:2, Informative)
Re:Test of a language (Score:2)
Are you sure? In the typical case, the list is split evenly in half, with n/2 items in the left side, and n/2 items in the right. Therefore at recursion frame k there are n/2+n/2=n items in memory. Since the list will split log n times, there are log n recursion frames, which means n log n memory in use at the deepest level of recursion.
Have I missed something subtle here?
Re:Test of a language (Score:2)
I guess that shows I do much more time analysis than space analysis...
Silly trolling article writer. (Score:5, Informative)
A mention of the Psyco [sourceforge.net] Python runtime compiler is in order. It's simple to use as well - all you do is put this at the top of your entry script: All routines called are then compiled from bytecode on-the-fly into native x86 code. It's not quite as fast as C - but with Psyco you can easily get close, especially if you design your algorithms properly.
While I'm here, these are the Python packages that I find essential once I have the base installation [python.org] (which includes the IDLE IDE). I've used these packages under Windows, but most work on Linux as well:
Re:Silly trolling article writer. (Score:3, Interesting)
Pyrex [canterbury.ac.nz]
You need a book? (Score:5, Funny)
You need a book to learn Python?!??!!? My god, I'm an old C++ programmer, Python is like a gift from a god!
You just have to bang your head against the keyboard a couple of times and I bet you it compiles!
Re:You need a book? (Score:2, Funny)
What would be nice ... (Score:2)
Is a book review that wasn't for lavae [catb.org].
It's like going to the local bookstore and hoping for something more to buy than Learn VB in 24 Hours.
I would love to use Python (Score:5, Insightful)
That said I can't justify the switch. There are just too many good modules available in Perl (esp for the engineering work I do). When python has the bredth of packages that Perl does, and when they have a nicely organized way to access said modules, I'll be happy to switch.
My review (Score:2, Insightful)
Re:My review (Score:2)
Perhaps they might want a more Agile language, instead of clunky C++/Java they are using at the moment? Going with Python, they can retain the scalability while developing code/unit tests/prototypes much faster. Being primarily a C++ programmer, getting to program in Python is extremely liberating. It feels like being able to talk fluently again, instead of measuring every word carefully and th
Re:My review (Score:2)
Apparently you've never worked on a project with a "core" header file that gets #include'd by about 5000 source modules. Make one little diddly change to that header and you have to recompile 5000 files.
It can sure as hell be a massive waste of time. Now, whether or not it's good practice to structure your program in such a way that everything depends on a single head
Re:My review (Score:4, Informative)
Important correction - Perl can look like assembler... but it doesn't have to. A Perl script can be as clean and readable as you want it to be. Ugly code is a result of lazy programmers, not the language itself.
Re:There's one major reason I choose Python over P (Score:2, Interesting)
Re:There's one major reason I choose Python over P (Score:3, Informative)
http://www.linuxjournal.com/article.php?
Re:There's one major reason I choose Python over P (Score:4, Interesting)
OTOH, Perl as a language is unbelievably flexible and convenient to work with, but it's most definitely a more "hackish" language, in that it's grown more than it's been designed. As such, it's definitely more of a developer's language (ie, has many of the features which, while not necessarily incredibly elegant, are *really* convenient) than a theorist's language.
So, then, why pick one over the other? Frankly, in the end, I suspect it's just personal preference (or predjudice).
Re:There's one major reason I choose Python over P (Score:2)
I think this depends a lot on 1) the application and 2) the chosen architecture. I've written some rather largish Perl projects (well, not that large... ~8000 lines) with little difficulty. It really just depends on the choice of design and how well Perl's language features match that design.
Re:There's one major reason I choose Python over P (Score:3, Informative)
Re:There's one major reason I choose Python over P (Score:3, Interesting)
I sort of hope that Parrot will help Perl overcome its introversion, and let it integrate more readily with other languages.
I think that C++ and Python form a dynamic duo. You can put the effort into compiling items that benefit from such, and glue them together in Python most agreeably.
The C++ standard library focused on Platonic abstractions, but Boost is pulling C++ in more mainstream directions. And that's a beautiful thing.
While issuing random plugs, check out Leo [sourceforge.net]. It's not too ofte
Re:There's one major reason I choose Python over P (Score:2)
Re:There's one major reason I choose Python over P (Score:2)
This turned me off of python for a while, and through the 1.x series of python, the answer was pretty much that python indeed did not have much over perl. I'm astonished perl still doesn't have formal parameters, but that's more a glaring lack in perl than a novel feature in python. Lack of funky "decorations" on variables
Now python
Re:There's one major reason I choose Python over P (Score:4, Informative)
Re:There's one major reason I choose Python over P (Score:5, Informative)
Python doesn't have static typing; it has dynamic typing like Lisp, Ruby, Perl, etc. The difference between Python and Perl is that Perl has rather weak dynamic typing. For example, Perl tries to treat strings and numbers as the same type (resulting in the use of strange constructs such as the value "0 but true"). Python and most other dynamically typed languages have stronger typing, with distinctions between strings, integers, floats, etc.
Static typing means that each variable is only allowed to hold values of one type. Usually the variable types are manually declared (as in C or Java), but some languages (like Haskell, IIRC) can infer the types.
Re:There's one major reason I choose Python over P (Score:3, Funny)
Re:There's one major reason I choose Python over P (Score:5, Informative)
Strong typing is when your language will only allow appropriate operations to be performed on values of the appropriate type.
Weak typing is the opposite, where a language will implicitly convert between (possibly incompatible) types or will simply allow any operation to occur.
Static typing is when a language enforces its typesystem (whether it be strong or weak) at compile time.
Dynamic typing is the opposite, when a language enforces its typesystem at runtime.
Python is strongly, dynamically typed. If you try to perform an integer operation on a string, it will check this at runtime and raise an exception. It will not perform the operation.
Perl is weakly, dynamically typed. If you try to perform an integer operation on a string, it will implicitly convert that string to an integer (using 0 in the case of strings that aren't a valid representation of an integer). It does this at runtime.
Haskell is strongly, statically typed. If the compiler cannot prove that all your operations are performed on values of the appropriate type, it will not compile your program.
C is weakly, statically typed. It will implicitly convert beteween incompatible values (pointers and ints, for instance) but it will determine which implicit conversions will occur at compile time (as well as reject some other conversions or type errors).
Python is not in any way statically typed. Perhaps only moderators who actually know Python should get mod points on articles such as these (yes, I know that'd be impossible, but it'd ridiculous that the parent post got modded up to 5, interesting when it's blatantly and obviously wrong).
Jeremy
Re:There's one major reason I choose Python over P (Score:2)
Jeez, it's good to issue a correction, but the error was in name only, the concept he was trying to express is still perfectly valid.
Re:There's one major reason I choose Python over P (Score:2)
Not that there are a great many dynamically scoped languages around these days...
Re:There's one major reason I choose Python over P (Score:2)
That's not weak typing. That's simply automatic conversion of types in some cases. Weak typing is like that of Forth, where if you add a float to an integer, the BIT PATTERNS are simply added together, as if both of them were integers.
Python is strongly, dynamically typed. If you try to perform an integer operation on a string, it will check this at ru
Re:There's one major reason I choose Python over P (Score:3, Insightful)
Re:There's one major reason I choose Python over P (Score:2)
uh? Care to differentiate between lists and arrays? Or are you trying to spread a little FUD to make it sound more complicated then it is.
Explain how using and referencing extra dimensional data types (list and hashes) are different in Python.
Re:There's one major reason I choose Python over P (Score:2)
There's one major reason I use scheme instead of silly languages like Python or Perl, lack of static typing. Scheme's type predicates are much more flexible.
Re:Python and Perl... (Score:3, Funny)
> a real Unix professional can do with Python
> or Perl that he or she can't do with awk, sed,
> and grep.
Awk? Sed? Bah! There's nothing you can do in awk and sed that you can't do with plain, simple assembly language opcodes!
Re:Python and Perl... (Score:2)
Amateur. Real programmers use nothing but S, K, and apply. [eleves.ens.fr]
Re:Python and Perl... (Score:2)
errr, actually, you only need one: Subtract and Branch if Negative [coventry.ac.uk]
Re:Python and Perl... (Score:3, Insightful)
Re:Bad foundations. (Score:5, Informative)
Python's intellectual ancestor was the language ABC, not Perl or TCL. Python's object system is very clean and well thought out, not accreted into the language. New style classes are an elaboration of that, merging the concept of a type and a class.
I'm not sure which "aspects from Camel" fuck up the whole situation. You're one example about continuations and GC "occultism" doesn't really help. 99% of the wonderful Python applications out there have no need of such stuff, and if you did, maybe Stackless Python (a variant) might interest you.
Python has all the necessary features to build very robust and maintainable systems. It's library is excellent, and it's C API is extremely clean for both embedding and extending.
A valid criticism for *some* applications is that it's slower than C or C++. This should come as no surprise since Python is interpreted and highly dynamic. Fortunately, Python can easily be extended such that critical sections can be coded in C, although most applications won't need to bother. It's also an excellent prototyping language so that if you *did* want to rewrite it in a static language like C++, you'd have an excellent basis for it.
swallowing the flamebait (Score:5, Insightful)
No way in hell. Python tries its best to avoid perlisms, and TCL/Tk doesn't even come close. Python has a strongly typed object system with one namespace.
I don't think that we really have to discuss the problems of Perl's "object system"
Perls object system is a hack. Python object system fits like a glove. ISTR that Larry kinda "copied" the objsystem from Python (and not vice versa), but it didn't really fit perl.
or the shortcomings of TCL/TK.
Shortcomings of TCL/Tk have really nothing to do with the topic. Don't try to sneak TCL/Tk into this. This has got to be the clumsiest strawman argument I've seen in a while. Chewbacca lives on Endor?
The result can be seen when you try to program a caller frame instance-preserving continuation in Python.
What do you mean? Closures (or "nested scopes" as they are referred to in the language docs - look them up before whining) work as expected. Can you give an example of the thing you are talking about in a language you know (assuming you know one). Are talking about what Stackless Python is trying to do?
But when the project advances they suddenly notice that python doesn't provide all necessary features and a whole rewrite is in order.
You don't really need "features", you can use libraries to add "features" and the core language is flexible enough for pretty much any tasks.
Re:Bad foundations. (Score:5, Insightful)
Yeah, it's really sad how many large projects fail because they're implemented in a language that doesn't properly support continuations....
Wait a minute, I've been in the computer industry for decades, and other than myself, I could probably count on one hand the number of people I've met who even know what a continuation is. Other than as an amusing tool to utterly confuse any but the most advanced developers, continuations are probably only useful for coroutines, and coroutines are mostly useful for iterator generators, which recent versions of Python have generators nicely packaged in an easy-to-understand syntax (the yield statement).
Since few if any other popular languages give you even this much, it must be truly amazing that any software works at all.
Re:Bad foundations. (Score:3, Informative)
Continuations are also incredibly useful for massively scalable network applications. They are arguably the best way to write them, in terms of code readability and performance.
Re:While we're on the subject of Python (Score:4, Interesting)
It's too easy to accidentally use do-while when you should have just used while. It actually makes the language less error-prone, because in those few cases where you do have an unconditional first pass, you are forced to structure the code differently and actually think about what you're doing.
You can always transform: do stmt while foo into stmt while foo stmt which isn't even longer (if stmt is actually many statements, it should be a function anyway). It's not worth introducing an abusable language construct just so you get to be lazy and not code a function when you should.
Re:Python getting to big (Score:2)
Criticizing Python because of the new features, modules, etc. really isn't warranted. Python hasn't lost its cohesion. You simply haven't kept up.
And yes, I have done Python full time. And yes, it was about 3 years ago. So yes, I will need to catch up at some point too. But it's not anyone else's fault
Re:Python getting to big (Score:2)
BUT....
You'd be missing out. Everyone gets bugged by how much things keep changing, and it is a problem. But what's the alternative? I've worked on VB, VB.NET, Java, and Python projects and they all keep ch
Re:Still doesn't have a maintained, up-to-date (Score:3, Informative)