Subscribe by RSSPython vs. Perl
Perl folk seem not to like Python, at least not at first glance. It's easy to understand why: the languages serve similar purposes, but have annoyingly different syntax and structure. There have been converts, though, and Eric S. Raymond's experiences are probably not atypical.
I've noticed that Linux Journal has had more than a few Python articles, and the most recent issue has begun a tutorial series. That article prompted me to take a more serious look.
First Impressions
I went to http://www.python.org/doc/current/index.html and used the excellent tutorial there. I found things to like and things to dislike immediately:
Liked
- That object methods are the default, not something tacked on:
a=['abc','def','ghijkl']
print "Before Append",a
a.append('hello')
print "After Append",a
...
Before Append ['abc', 'def', 'ghijkl']
After Append ['abc', 'def', 'ghijkl', 'hello']
There's a whole boatload of built-in methods: see http://www.python.org/doc/current/tut/node7.html. I'm not going to say I like these better than the Perl functions that do similar things, but I certainly have no problems with these and can see good use for them.
- That integer math is the default unless one or more of the
operands isn't an integer:
print 7 / 2
print 7.0 / 2
...
3
3.5 - That semicolons at the end of lines are optional: any of these
are fine:
print 7/2;print 7/2.0
print 7/2;
print 7/2.0
print 7/2
print 7/2.0Leaving off semicolons is a common Perl goof..
- Indentation syntax. Everything indented is part of what happens
when "mytest" is not 0 or null:
mytest=1
if mytest:
print "mytest ",
print "is set"
print "hello ",Oddly, this is something most Perl types really hate, but I'd find it easy to get used to. Since most of us tend to indent code within blocks anyway, it seems reasonable to me to dispense with the braces and just use the indentation.
- Default argument values for functions:
def foo(prompt="huh?", count=2):
print prompt,count
foo()
foo("go","seven")
foo(count=89)
...
huh? 2
go seven
huh? 89I really like that.
- Exception handling. I like "try/except" logic (apparently Perl 6 has this too);
Disliked
- Variables. I don't like the C-ish variable names. I LIKE that Perl requires a $, @ or whatever ahead of a variable name - it makes it stand out. I also like that Perl's $a is different than @a etc.
- Data types. Setting a one value tuple is absolutely ugly:
this='abc','def',0;
print this, len(this)
this='hello' # NOT a tuple
print this, len(this)
this='hello', # Now it is
print this, len(this)
...
('abc', 'def', 0) 3
hello 5
('hello',) 1
This is a consequence of not having data prefixes or formal declarations.
- No "a++" or "a--". Sheesh.
- No "$_". There's _, which apparently isn't quite the same - unless I misunderstand, which is certainly possible at this point.
Overall, I think I'll stick with Perl. I can see Eric Raymond's argument for larger projects, but I don't do large projects anymore and I just find Perl's wild versatility and lack of insistence (More Than One Way To Do It) more attractive than more structured languages. But Python certain does have its appealing aspects, so I'll probably dabble with it here and there.
I certainly cannot agree with some who insist that Python is easier to read or understand than Perl. That's just ridiculous: neither of them add anything to helping understand someone else's code. Perl isn't any more "cryptic" than Python. Nor can I understand the attitude that Perl is deficient because you can do things in multiple ways. If you insist on such structure, enforce it upon yourself: nobody is stopping you. I do understand that for larger projects, with multiple people involved, structure is more necessary.
All in all, I wouldn't be terribly upset if I got "stuck" with something that had to be done in Python. It's a very reasonable scripting tool and does have some very nice features.
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PythonVsPerl :
"Overall, I think I'll stick with Perl. I can see Eric Raymond's argument for larger projects, but I don't do large projects anymore and I just find Perl's wild versatility and lack of insistence (More Than One Way To Do It) more attractive than more structured languages. But Python certain does have its appealing aspects, so I'll probably dabble with it here and there."
I tend to agree here. Perl just seems to be more flexible -- almost like BASIC in many ways, and if I'm trying a quick hack-together, I'd rather not have to deal with Python's pendantic tendencies.
"I certainly cannot agree with some who insist that Python is easier to read or understand than Perl. That's just ridiculous: neither of them add anything to helping understand someone else's code."
How true. Unless you really understand how someone else thinks, how are you going to truly surmise what was intended by looking at uncommented code? I look at some of my old, uncommented code (especially 65xx M/L) and *I* can't figure out what in blue blazes I was thinking.
"Nor can I understand the attitude that Perl is deficient because you can do things in multiple ways. If you insist on such structure, enforce it upon yourself: nobody is stopping you. I do understand that for larger projects, with multiple people involved, structure is more necessary."
For more structure, use C. <Smile>
My impression of some of these johnny-come-lately languages (e.g., Python) is that they were developed by folks who couldn't think in ways supported by other languages or simply don't like adhering to established practices. While the latter isn't necessarily a bad thing in computerdom, it also isn't always good. Just take a look at the Microsoft mess for an excellent example.
In any case, just how many languages does a bloke have to know to make a living? According to my wife, there's so much gobbledy-gook (her term for any programming language) in my head, any semblence of normal thinking disappeared years ago.
--BigDumbDinosaur
Mon May 30 12:23:16 2005: Subject: More Info Would be Great anonymous
I'd like to read about the differences in object orinted programming features. Can Python/Perl do the same things Java does (encapsulation, polymorphism etc.)? I know not natively, but with some modules Perl does that I guess - what about Python?
Mon May 30 12:33:36 2005: Subject: TonyLawrence
I'm not a big OO fan, so I pay very little attention to those capabilities in any language. I'm not anti-OO: I think it is good in some places, but usually not for the kinds of things I do.
Tue Jul 26 09:20:43 2005: Subject: drag
Interesting.
I played around with python a bit more then perl. I like how it's generally easier to read.
Haven't quite been able to get my head around making my own classes yet, but I am working on it.
I don't know what you mean by 'polymorphism' and 'encapsulation' and such.. but Python is suppose to be very OO-freindly from what I understand. If your building a application, for instance, and you run into a part that is very performance-oriented bottleneck you can then go and rewrite that part of the program in C, which isn't to hard since it has a c-alike syntax (and I think there are things that will take python code and translate it to c for you, not sure). Then you can compile it and import that back into your python program as a module. You can import other programs back into your python program and use their functions and classes and such in your programs..
For instance if you have a program and you want to have a GUI for it, and a command line interface for it.. You could create a core functionality with the main logic of the program as a seperate peice then create a GUI front end, and then a seperate command line front end then import that functionality into your programs.
Also Python isn't a interpreted language so much like Basic is.. It's compiled into optimized bitecode in the form of object files the first time you call something and then you use that. Any changes to the source code that you call will cause it to re-generate the bitcode..
Python is unusual because it's 'strongly typed' and 'dynamicly typed'. It's strongly typed like Java.. you can't simply change types depending on the circumstances, but it's dynamicly typed like VBScript were the program decides what type on the fly when you create the the datatype.
There are a few conventions that you have to get used to. For instance the tuple thing... generally you use paranthesis to easily denote tuple creation, and you use capitolization to denote variables and such, depends on the programmer I support.
This=('tuple',)
type(This)
That's a tuple, obviously.
This=['tuple',)
type(This)
That's a list. So you can create your datatypes specificly if you like.
Another convention is that if your working with numbers...
This=4
type(This)
Will be a int.
This=4.0
type(This)
Will be a float.
But you can specificy if you want..
This=float(4)
type(This)
that will be a float. And:
This=int(4.0)
type(This)
will be a init. It rounds down, so...
This=int(4.9)
print This
4
This=str(4.9)
type(This)
will be a string...
This is kinda handy:
This=hex(454)
print This
'0x1c6'
You can do the same thing with tuple() and list() if you want and there are a couple other datatypes that I forget.. But you have to be carefull...
This=tuple("tuple")
print This
('t', 'u', 'p', 'l', 'e')
When doing mathmatics generally you want to add one number with a decemal to it just so you get the result of the entire formula as a float.
That's what I use python mostly for... Mathmatics. It's very handy for that sort of thing. Lots of libraries and handy dandy functions and such you can import from other programs. Also very high-level math is attanable as long as you mind the limitations. There are scientific modules and engineering stuff you can use. I seen on PBS once that this professor programmed 3-d plotting of tornadoes based on his formulas for weather simulation entirely in python. So I think that it's commonly used programming language by enginneers and such.
In fact I prefer to use python to scientific calculators if I can.
I don't think that math and such is a strong point for Perl, although I never realy use perl much at all, so I can't be sure. But it's a hell of a lot better then Bash.
Official docs...
http://www.python.org/doc/
They talk a bit about other languages and do comparisions.
One odd thing about Python is that although it's slow (and can be sped up sometimes by liberal applications of the 'psycho' module), it has a agressive garbage collector so the memory footprints of python programs remain small compared to stuff like Java.
If your a experianced programmer then this book is probably quite handy introduction to python:
http://diveintopython.org/
All in all it's actually a 'fun' programming language. There are modules for making things (relatively) easy, lots of sharing of code. Lots is out there..
you have a weird data collection card? There is probably somebody using python modules for data collection. You want to make games.. there are several python-related gaming engines and library support like libsdl modules. It's used as a scripting language for Blender, a popular and full-featured 3d modeling suite. You need more 'exact' 3d solutions for moduling things and use in programs there are several commercial and free software solutions to choose from.
All sorts of stuff. And if your making things for the win32 platform you can even compile your python programs into self-contained .exe executables so that the end users don't have to track down all these dependancies and libraries and such.
Tue Jul 26 14:39:17 2005: Subject: BigDumbDinosaur
Also Python isn't a interpreted language so much like Basic is.. It's compiled into optimized bitecode...
However, the "bytecode" itself is interpreted.
You should know that all forms of Business BASIC are stored in optimized form (tokenized or bytecode, if you prefer). For example, Thoroughbred BASIC, which is an environment in which I've done a lot of development, reduces verbs such as PRINT or READ to byte or word sized tokens, generates an internal symbol table for fast variable and branch target lookup, and generally compacts the program (as much as 20 percent smaller than the source text). Only lame BASIC versions like MS-DOS's Qbasic store the program in ASCII text form, making for slow interpretation. Even the BASIC interpreter that ran on the Commodore 64 tokenized programs.
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