Why I Love Python V2

The language you speak affects what you can think By learning multiple languages, I can think more broadly and create better designs

Reduces rigid thinking

Does Language Matter?

From “Sway”: Fear of loss -> Playing “not to lose” Commitment

Static analysis is very useful But it should be decoupled from the language Allows more experiments; faster addition of new tests Python benefits from more static analysis tools Why I Love Python ©2008 www.MindView.net

Optional Static Typing Scott Meyers: Static typing is for development tools and code generation. ActionScript (the Flex language) is a dynamic language with optional static typing FlexBuilder gives code hinting when you provide type information But you can turn it off whenever you want Something like what Python 3 allows Why I Love Python ©2008 www.MindView.net

ActionScript package com.mindviewinc.functional { public function reduce(a:Array, reducer:Function):* { var result:* = a[0] for each(var item:* in a.slice(1, a.length)) result = reducer(result, item) return result } }

Is Programming Art or Engineering?

Many Companies Desperately Want it to be Engineering Replaceable You

What I love most: Python is about ME As if Guido said: “Bruce, what can we do to make your programming experience as easy as possible?” No compromises: it’s all about making me more productive Why I Love Python ©2008 www.MindView.net

A ‘Bout’ of Perl After C++ and Java, seemed amazing Python is executable pseudocode. Perl is executable line noise. Perl is like vice grips. You can do anything with it, and it's the wrong tool for every job (Leaves teeth marks everywhere) Perl is worse than Python because people wanted it worse. Larry Wall, 14 Oct 1998 I would actively encourage my competition to use Perl. Sean True, 30 Mar 1999 Why I Love Python ©2008 www.MindView.net

Python Reduces Clutter Programs are read more than they are written Consistent formatting really is important Readability and compactness Conservation of complexity: Simplicity really does make a difference Consistent use of programming idioms improves understandability Rapid understanding The opposite of “more than one way to do it” Why I Love Python ©2008 www.MindView.net

It doesn’t value performance over my productivity C++: can’t let go of C performance Better than C, sure, but still takes forever to get something working; memory leaks are almost impossible to design out Java: Primitive types require awkward coding (primitives “necessary” for speed) As opposed to Python: everything is an object; escape mechanism for speed: ctypes Why I Love Python ©2008 www.MindView.net

It doesn’t treat me like I’m stupid “Operator overloading is bad because you can make ugly code with it” “finalize( ) does something” “We reviewed Java designs before putting them into the language” AWT & EJB are great, Swing is easy, JavaFX will be great! “Every new feature makes it better! Generics! Closures!” Why I Love Python ©2008 www.MindView.net

Pro Con Garbage collection is now Dumb naming. Java 2 is mainstream 1.2, Java 5 is 1.5. Also Virtual nio and nnio. Naming is machines/bytecode important. interpreters are now Classpath (enough said) mainstream Bad invention in general Unified error handling vs. Added-on features to C++ compensate for bad language design Never admitting that the design was bad in the first place Checked exceptions. Sound good, don't scale Why I Love Python ©2008 www.MindView.net

Con Con Primitives (but they like to Assertions: they're off by call the language \"pure”) default; you have to turn Knee-jerk threading, them on via a command- which is confusing and line flag too hard to get right. Generics (so-called) w/ Subtle threading bugs erasure. Not really until Java 5 generics, just support for They *had* to rush it out, collection typing. Even now they're one of the architects has monkeypatching the reversed position. language Now closures! But this Faked properties and has rapidly become a events (JavaBeans) mess with lots of push- back, no doubt because of generics. Why I Love Python ©2008 www.MindView.net

Con Con The EJB fiasco (many AWT was too simple & billions lost) bad. Swing is too The JCP: Panders to complex, but Sun has a every special interest and deathgrip on it (sunk cost pushes the results on us model). Now we have (you get 10 days to JavaFX instead of playing comment) well with, say, Flex which has already solved the problems. I could go on. Why I Love Python ©2008 www.MindView.net

Con Pro Self (Everything else) GIL is unavoidable, but Biggest: I trust Guido, the we need a pythonic team, and the community. concurrency model (don't Choices that seem weird just use threads because at first turn out to be good everyone else does). (comprehensions). Need a one-click installer Things that are broken as part of the distribution. get fixed (XML library, An easy_install type of refactoring in Python 3). service should also be I'd like to just work with built in. Python and Flex. Currently, for me, that's the best of all worlds. Why I Love Python ©2008 www.MindView.net

It doesn’t make assumptions about how we discover errors Is static type checking really the only way to be sure? Lack of good static typing in pre-ANSI C was certainly heaps of trouble Doesn’t mean it’s the best solution Errors discovered with real data seem to me to be the hardest to find statically Why I Love Python ©2008 www.MindView.net

I don’t have to type so much … And I don’t have to wade through so much code when I’m reading But the right typing Not obscure like APL Not endlessly inventive like Perl or FORTH Why I Love Python ©2008 www.MindView.net

The clean design of the language encourages clean library design: import feedparser rss = feedparser.parse('myurl.rss') for entry in rss['entries']: print entry['link'], entry['title'], entry['summary‘] Why I Love Python ©2008 www.MindView.net

My guesses are usually right Most things in Java require me to look something up I can remember many Python idioms because they’re simpler One more reason I program faster Why I Love Python ©2008 www.MindView.net

I can remember this: file(\"Myfile.txt\") I always have to look this up: import java.io.*; BufferedReader in = new BufferedReader( new FileReader(\"Myfile.txt\")); Why I Love Python ©2008 www.MindView.net

Duck (Structural) typing Only constraints on an object that is passed into a function are that the function can apply its operations to that object def sum(arg1, arg2): return arg1 + arg2 print sum(42, 47) print sum('spam', 'eggs') If it walks like a duck, and talks like a duck… Why I Love Python ©2008 www.MindView.net

Duck Typing in C++: Templates #include <string> #include <iostream> using namespace std; template<class A, class B, class R> R sum(A a, B b) { return a + b; } int main() { string a(\"one\"), b(\"two\") cout << sum<string, string, string>(a, b) << endl; cout << sum<int, int, int>(1, 2) << endl; } Why I Love Python ©2008 www.MindView.net

interface addable { Object add(Object b);} class X implements addable { public Object add(Object b) { return new Object(); // Test } } class AddableNotFoundException extends Exception {} public class DuckTyping { public static Object sum(Object a, Object b) throws AddableNotFoundException { Class[] intfs = a.getClass().getInterfaces(); for(int i = 0; i < intfs.length; i++) if(intfs[i] == addable.class) return ((addable)a).add(b); throw new AddableNotFoundException(); } public static void main(String[] args) throws Exception { X a = new X(); X b = new X(); Object c = sum(a, b); } }

Duck typing isn't weak You write what you want to do, let Python worry about how Argument against dynamic typing: “errors won’t be found” Like in pre-ANSI C (had no rules) As long as rules are enforced sometime, you’ll find the errors Heresy: run-time is better than compile time Why I Love Python ©2008 www.MindView.net

Performance issues Machine Performance vs. Programmer Performance Most of the time, which is really more important? Python 2.5 cytpes easily connect to dlls pp and similar solutions for multiprocessor machines and machine clusters Why I Love Python ©2008 www.MindView.net

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Why I Love Python V2

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