Re: The Industry choice

[Peter Dembinski]

Paul Rubin  writes:

[...]

> I don't understand that.  If I see "str x = str(3)", then I know
> that x is a string.

def foo(x):
return str(x)

str = foo(x)

And now, let's say that foo()'s definition is in another module.
It is hard for a programmer to quickly determine the type for str,
that's the problem with programming in languages that don't have
type declarations.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

"Donn Cave" <[EMAIL PROTECTED]> writes:

[...]

> For me, the effect is striking.  I pound out a little program,
> couple hundred lines maybe, and think "hm, guess that's it" and save
> it to disk.  Run the compiler, it says "no, that's not it - look 
> at line 49, where this expression has type string but context 
> requires list string."  OK, fix that, iterate.

I believe program-specific unit tests are more effective than compiler
typechecking :)
-- 
http://mail.python.org/mailman/listinfo/python-list

[OT] Re: The Industry choice

[Peter Dembinski]

Paul Rubin <http://[EMAIL PROTECTED]> writes:

> Peter Dembinski <[EMAIL PROTECTED]> writes:
>> If it has to be both reliable and secure, I suggest you used more
>> redundant language such as Ada 95.
>
> That's something to think about and it's come up in discussions, 
> but probably complicates stuff since it's not currently available 
> on the target platform.  Also, the people on the project have 
> significant Java and Python experience but haven't used Ada.  
> Do you think it has real advantages over Java?

As I wrote before, it is more redundant language[1], plus (AFAIR) 
it has the strongest type checking of all the programming languages 
I know about.

Plus, most of Ada compilers (such as gnat) generate machine/operating
system - specific code[2], not bytecode, which could be advantage 
if performance is one of priorities.

I may have a little skewed viewpoint because Ada 95 is the language 
I have recently studied on my RTS labs :>


[1] for example, one has to define interface and implementation parts
of each module in separate files

[2] AFAIR gnat generates C code, which is then compiled with gcc.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

Peter Dembinski <[EMAIL PROTECTED]> writes:

[...]

> str = foo(x)

(ick!) it should be:

bar = foo(x)
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

Peter Dembinski <[EMAIL PROTECTED]> writes:

> Peter Dembinski <[EMAIL PROTECTED]> writes:
>
> [...]
>
>> str = foo(x)
>
> (ick!) it should be:
>
> bar = foo(x)

Besides, shouldn't str be a reserved word or something?
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

Bulba! <[EMAIL PROTECTED]> writes:

[...]

> The point is obviously "cover your ass" attitude of managers:

Managers get paid for taking risk :)
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

Peter Hansen <[EMAIL PROTECTED]> writes:

> Roy Smith wrote:
>> "Terry Reedy" <[EMAIL PROTECTED]> wrote:
>>
>>> None has been reserved because there is no known good use for
>>> overriding it.
>> Should I infer from the above that there's a known bad use?
>
> Yes: making None equal to the integer 3.  That's one of
> six known bad uses  it's possible there are more. ;-)

Binding user variables to these names should raise exception
(eg. AreYouInsaneException or WhatAreYouDoingException) :>
-- 
http://mail.python.org/mailman/listinfo/python-list

[OT] Re: The Industry choice

[Peter Dembinski]

Bulba! <[EMAIL PROTECTED]> writes:

[...]

> That's remarkable, first time I see smth like this - 
> out of curiosity, could you say a word where was that?

Are you the same Bulba I know from alt.pl.comp.os.hacking?
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

"Thomas Bartkus" <[EMAIL PROTECTED]> writes:

[...]

> > What makes such companies to choose Java over dynamic, productive
> > languages like Python?  Are there any viable, technical reasons
> > for that?
>
> Are there "viable, technical reasons"?  That would be doubtful.
>
> But
>
> There is a reason very important to major companies.  When you leave
> that company, there will be a *long* line of Java programmers
> waiting to take your place.

IMO learning Python is a matter of few days for Java programmer.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: The Industry choice

[Peter Dembinski]

Paul Rubin  writes:

[...]

> I'm involved in a development project for something that's security
> critical and has to be reliable.  The implementation language hasn't
> been chosen yet.  Python and Java are both possibilities.  I'm fine
> with the idea of using Python for demos and prototypes.  For the
> production system I think we may be better off using Java.
> Reliability of the final product is more important than rapid
> implementation.

If it has to be both reliable and secure, I suggest you used more
redundant language such as Ada 95.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Python + Lisp integration?

[Peter Dembinski]

Simo Melenius <[EMAIL PROTECTED]> writes:

> Hi,
>
> I'm wondering (after a bit of googling) whether there exists 
> a Python binding to any open source Lisp environment (like librep 
> or some Scheme or Common Lisp implementation) that could 
> be recommended for non-toy use?

Dunno about non-toy uses, but if you want program your emacs with
Python, there is pymacs available :)
-- 
http://mail.python.org/mailman/listinfo/python-list

Refactoring in Python.

[Peter Dembinski]

I am trying to write Master Thesis on refactoring Python code.

Where should I look for information?

-- 
http://www.dembiński.prv.pl 
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Refactoring in Python.

[Peter Dembinski]

Skip Montanaro <[EMAIL PROTECTED]> writes:

> Peter> I am trying to write Master Thesis on refactoring Python
> Peter> code.  Where should I look for information?
>
> I'm not sure, but one piece of code to check out would probably 
> be Bicycle Repair Man, a early-stage prototype refactoring tool 
> for Python.  I don't recall where it's hosted.  Google will know.

Well, I can't simply describe Bicycle Repairing Man in my thesis :)

The idea is to define some 'mechanics' for refactoring Python code
without specialized refactoring browser.  In other words, I want 
to convert Fowler's refactorizations to Python.

Similar work (or its seeds) is here:
http://hiper.com.br/python/refactor/index.html

-- 
http://www.dembiński.prv.pl 
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Refactoring in Python.

[Peter Dembinski]

[EMAIL PROTECTED] writes:

> Investigate the CVS histories of the few 1000s python projects
> available at www.sourceforge.net

I don't work with these guys :>

-- 
http://www.pdemb.prv.pl 
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Can .py be complied?

[Peter Dembinski]

[EMAIL PROTECTED] (John J. Lee) writes:

[snap]

> Until they install the next program that does this.

If we talk about _real_ users from the _real_ world, the most of them
would just kill the app (or what is the name for stopping running
program in w32) when the download begins[1] :)

[1] 'hey, is that a spyware or what?  what takes so darn long?'

-- 
http://www.pdemb.prv.pl 
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Python features

[Peter Dembinski]

On Sun, 08 May 2005 10:02:42 +0200, Andrà Roberge  
<[EMAIL PROTECTED]> wrote:

[...]

> google for "python" and "functional"; first link:
> http://www-106.ibm.com/developerworks/linux/library/l-prog.html

[...]

> Imperative programming languages are the most commonly used languages.  
> Examples of this type of language are C, C++, Ada, Fortran, Algol, Java,  
> Python, Perl, and so on.

How about lambda construction?  Isn't Python imperative language that
includes some functional mixins?

I mean -- can you say Python is fully imperative language?

If you want to redirect me to Google, don't bother.  IMO ninety percent
of writings found on WWW is just a garbage.

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: function with variable arguments

[Peter Dembinski]

On Fri, 13 May 2005 11:52:34 +0200, Xah Lee <[EMAIL PROTECTED]> wrote:

> i wanted to define a function where the number of argument matters.
> Example:
>
> def Range(n):
> return range(n+1)
>
> def Range(n,m):
> return range(n,m+1)
>
> def Range(n,m,step):
> return range(n,m+1,step)
>
> this obvious doesn't work. The default argument like
> Range(n=1,m,step=1) obviously isn't a solution.
>
> can this be done in Python?
>
> or, must the args be changed to a list?

It can be written this way:

   def Range_3args(n, m, step):
   return range(n, m + 1, step)

   def Range_2args(n, m):
   return range(n, m + 1)

   def Range(n, m = None, step = None):
   if (m is None) and (step is None):
   return range(n + 1)

   if (not (m is None)) and (step is None):
   return Range_2args(n, m)

   if (not (m is None)) and (not (step is None)):
   return Return_3args(n, m, step)

   return []


-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Precision?

[Peter Dembinski]

"Steffen Glückselig" <[EMAIL PROTECTED]> writes:

> Hello,
>
> I've just wanted to check Python's abilities as a calculator and this
> is what came out:
>
 1.0 + 3.0 + 4.6
> 8.5996
>
> Ehm, how could I get the intuitively 'correct' result of - say - 8.6?
> ;-)

This is as correct as your computer's FPU can made it :)

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: question about the id()

[Peter Dembinski]

Skip Montanaro <[EMAIL PROTECTED]> writes:

> kyo> Can someone explain why the id() return the same value, and
> kyo> why these values are changing?
>
> Instance methods are created on-the-fly.  

So, the interpreter creates new 'point in address space' every time
there is object-dot-method invocation in program?  

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: question about the id()

[Peter Dembinski]

[EMAIL PROTECTED] (Bengt Richter) writes:

[snap]

>>So, the interpreter creates new 'point in address space' every time
>>there is object-dot-method invocation in program?

[optimization]

> BTW, a typical performance optimization (not done automatically by python)
> is to hoist unchanging-value expressions out of loops, and obj.method is
> often such an expression, so you will this strategy when people try
> to squeeze extra performance from their programs.

Good to know.  Is there any advanced optimizer for Python code, which
would do such things for me (or suggest them, like pychecker does 
for readability)?

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: question about the id()

[Peter Dembinski]

"Giovanni Bajo" <[EMAIL PROTECTED]> writes:

> Peter Dembinski wrote:
>
>>> BTW, a typical performance optimization (not done automatically by
>>> python) is to hoist unchanging-value expressions out of loops, and
>>> obj.method is often such an expression, so you will this strategy
>>> when people try
>>> to squeeze extra performance from their programs.
>>
>> Good to know.  Is there any advanced optimizer for Python code,
>> which would do such things for me (or suggest them, like pychecker
>> does for readability)?
>
>
> Prove that a.f() would not change the meaning of "a.f" after its
> invokation is close to impossible.

Many things in Python programs cannot be proved.  But what about
suggesting optimisations, not doing them automatically?  

The similar case may be found in refactorization -- most things cannot
be proved, so the final decision is left to the programmer (and his
unit tests).

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: speeding up Python script

[Peter Dembinski]

"Luis P. Mendes" <[EMAIL PROTECTED]> writes:

> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA1
>
> Hi,
>
> I have a 1000 line python script that takes many hours to finish.
> It is running with six inside 'for' loops.
>
> I've searched the net for ways to speed up the proccess.
>
> Psyco improves performance around 3% in this case which is not good
> enough.
>
> How can I dramatically improve speed?

You are looking for better algorithm, not for Python optimisations.

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: How to learn OO of python?

[Peter Dembinski]

could ildg <[EMAIL PROTECTED]> writes:

> I have learned python for over a month.
> I heard that it was very easy to learn, but when I tried to know OO
> of python,
> I found it really weird, some expressions seem very hard to understand,
> and I can't find enough doc to know any more about it.

These may be hard to understand because you haven't understood OOP.
Python syntax is very similar to p-code used in computer science
books.  Try to think like a computer scientist :>

> So, I wonder how did you master python? And where to find some cool
> docs?

Go to the nearest library and get some OO design book.

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Is Python suitable for a huge, enterprise size app?

[Peter Dembinski]

"keirr" <[EMAIL PROTECTED]> writes:

[snap]

> I wouldn't, especially[1] if your thousands of business objects get
> allocated/deallocated as the system runs.  Currently python's memory
> usage can grow rapidly (from the perspective of the o/s) when large
> numbers of objects are repeatedly created and freed.

Isn't it true that in recent Python releases, one may replace the
default GC with custom one?

> On the other hand, you could use a combination of python and C++
> (perhaps using boost's python wrapping code).  The ability to create
> C/C++ modules is a "get out of jail free card" - if you did manage
> to convince your company to go with python, and it fell short in
> some area, a custom C module could be a handy trick.

In fact, it is not a trick -- combining C with Python is fairly
approved way of speeding up the app :)

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Access lotus notes using Python

[Peter Dembinski]

"Sateesh" <[EMAIL PROTECTED]> writes:

> Hi,
> Is it possible to access Lotus notes using Python? Can anyone
> provide me some pointers?

jython + LN Java bindings may be usable

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: What are OOP's Jargons and Complexities?

[Peter Dembinski]

"Xah Lee" <[EMAIL PROTECTED]> writes:

[snap]

put it on your blog

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: idiom for constructor?

[Peter Dembinski]

Steven Bethard <[EMAIL PROTECTED]> writes:

> Mac wrote:
>> Is there a nice Python idiom for constructors which would expedite
>> the following?
>> class Foo:
>>   def __init__(self, a,b,c,d,...):
>> self.a = a
>> self.b = b
>> self.c = c
>> self.d = d
>> ...
>
> py> class Foo(object):
> ... def __init__(self, a, b, c, d):
> ... params = locals()
> ... del params['self']
> ... self.__dict__.update(params)
> ...
> py> vars(Foo(1, 2, 3, 4))
> {'a': 1, 'c': 3, 'b': 2, 'd': 4}
>
> Just make sure that "params = locals()" is the first line in
> __init__ method.  (Otherwise you might have other local variables
> slip in there.)

Or write it like this, using Python's dynamic code execution:

#v+

class A:
def __init__(self, a, b, c, d):
initial = {'a' : 1, 'b' : 2, 'c' : 3, 'd' : 4}

for param in initial.keys():
exec "self.%s = initial['%s']" % (param, param)

#v-

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: idiom for constructor?

[Peter Dembinski]

Peter Dembinski <[EMAIL PROTECTED]> writes:

[snap]

Eh, sorry, it should look like this:

> #v+
>
> class A:
> def __init__(self, a, b, c, d):
> initial = {'a' : 1, 'b' : 2, 'c' : 3, 'd' : 4}  
  initial = {'a' : a, 'b' : b, 'c' : c, 'd' : d}
>
> for param in initial.keys():
> exec "self.%s = initial['%s']" % (param, param)
>
> #v-
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: idiom for constructor?

[Peter Dembinski]

Steven Bethard <[EMAIL PROTECTED]> writes:

> Peter Dembinski wrote:
>>class A:
>>def __init__(self, a, b, c, d):
>>initial = {'a' : a, 'b' : b, 'c' : c, 'd' : d}
>>for param in initial.keys():
>>exec "self.%s = initial['%s']" % (param, param)
>
> This is not a good use case for exec.  Use setattr:

OK, true.
>From the other side: what are the usual uses of 'exec'?
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Scope

[Peter Dembinski]

Elliot Temple <[EMAIL PROTECTED]> writes:

> I want to write a function, foo, so the following works:
>
> def main():
>  n = 4
>  foo(n)
>  print n
>
> #it prints 7
>
> if foo needs to take different arguments, that'd be alright.
>
> Is this possible?

It is possible, but the more natural way would be to use function
return value:

   n = f(n)

or, if you need many assignments:

   a, b, c, d = f(a, b, c, d)

and, respectively:
   
   return a, b, c, d

in the function's body.

> I already tried this (below), which doesn't work.  foo only changes
> the global n.
>
>
> n = 3
> def main():
>  def foo(var, context, c2):
>  exec var + " = 7" in context, c2
>
>  n = 4
>  foo("n", locals(), globals())
>  print n
>
> if __name__ == '__main__': main()
>
> print n

You need to make 'n' globally visible.  See the 'global' keyword 
in Python user manual.

> And of course I tried:
>
>  >>> def inc(n):
> ...  n += 3
> ...
>  >>> a = 4
>  >>> inc(a)
>  >>> a
> 4

AFAIK inc is builtin function.  And builtin functions doesn't have to
be real functions, they can be just aliases to Python's VM bytecodes
or sets of bytecodes.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Scope

[Peter Dembinski]

Steven Bethard <[EMAIL PROTECTED]> writes:

> Peter Dembinski wrote:
>> AFAIK inc is builtin function.  And builtin functions doesn't have
>> to be real functions, they can be just aliases to Python's VM
>> bytecodes or sets of bytecodes.
>
> Wrong on both counts. ;)

Yup.  My mistake.

[snap]

> And while builtin functions may not have to be real *functions*,
> they do have to be real *callables*:

Yes.  I discovered it yesterday.

[snap]

> Note that both  and 
> have a __call__ method, which means they are callable objects.
> They're not just bytecodes; they're real objects, just like
> everything else in Python. =)

Yup.  True.

-- 
http://www.peter.dembinski.prv.pl
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: python bytecode grammar

[Peter Dembinski]

"Terry Reedy" <[EMAIL PROTECTED]> writes:

> "M1st0" <[EMAIL PROTECTED]> wrote in message 
> news:[EMAIL PROTECTED]
>> where I can find the grammar of python bytecode ? ( better if is in
>> BCF
>
> I believe the top-level production is something like
> BYTECODE := (OPCODE ARGS)*

ROTFL :)
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: How to get/set class attributes in Python

[Peter Dembinski]

Kalle Anke <[EMAIL PROTECTED]> writes:

[snap]

>> sys.maxint = -12345
>
> I don't really understand what you're meaning.

He meant None = 1 :>
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: How to get/set class attributes in Python

[Peter Dembinski]

"vincent wehren" <[EMAIL PROTECTED]> writes:

> "Peter Dembinski" <[EMAIL PROTECTED]> schrieb im Newsbeitrag 
> news:[EMAIL PROTECTED]
> | Kalle Anke <[EMAIL PROTECTED]> writes:
> |
> | [snap]
> |
> | >> sys.maxint = -12345
> | >
> | > I don't really understand what you're meaning.
> |
> | He meant None = 1 :>
>
> I'm sure you know that has become a no-no in Python 2.4+ ;)

Yep.  Still waiting for delegalisation of others :>
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: How to get/set class attributes in Python

[Peter Dembinski]

Bruno Desthuilliers <[EMAIL PROTECTED]> writes:

[snap]

>> Being an untyped language, Python does not require you to enforce
>> types.
>
> Nope. Python *is* typed. But it doesnt confuse implementation 
> with semantic.

Python is typed.  And its type system may look strange for anyone who
did only Java or C++ programming before :>
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: What is different with Python ?

[Peter Dembinski]

Steven D'Aprano <[EMAIL PROTECTED]> writes:

[snap]

> new_text = ""
> for word in text:
> new_text = new_text + process(word)

new_text = "".join(map(process, text))

(I couldn't resist)
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: How to get/set class attributes in Python

[Peter Dembinski]

Chris Spencer <[EMAIL PROTECTED]> writes:

> Peter Dembinski wrote:
>> Bruno Desthuilliers <[EMAIL PROTECTED]> writes:
>>
>>> Nope. Python *is* typed. But it doesnt confuse implementation with
>>> semantic.
>> Python is typed.  And its type system may look strange for anyone
>> who did only Java or C++ programming before :>
>
> Of course, in that Python is dynamically typed as opposed to the
> static typing of Java or C++. Please excuse my previous mis-wording :)

Mis-wording?
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: python bytecode grammar

[Peter Dembinski]

"Terry Reedy" <[EMAIL PROTECTED]> writes:

> "Peter Dembinski" <[EMAIL PROTECTED]> wrote in message 
> news:[EMAIL PROTECTED]
>> "Terry Reedy" <[EMAIL PROTECTED]> writes:
>>> I believe the top-level production is something like
>>> BYTECODE := (OPCODE ARGS)*
>>
>> ROTFL :)
>
> Glad to make your day ;-)

You are welcome.

"Asking stupid questions is the best way to get quick answers" :>
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: implicit variable declaration and access

[Peter Dembinski]

Benji York <[EMAIL PROTECTED]> writes:

[snap]

>> code = x + '= 0'
>> exec(code)
>
> You should generally stay away from exec for lots of reasons.

Code 'refactorizability' is one of them.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: implicit variable declaration and access

[Peter Dembinski]

Tom Anderson <[EMAIL PROTECTED]> writes:

[snap]

> The MAtrix had evarything in it: guns, a juimping off teh walls,
> flying guns, a bullet tiem, evil computar machenes, numbers that
> flew, flying gun bullets in slowar motian, juimping into a gun, dead
> police men, computar hackeing, Kevin Mitnick, oven trailers, a old
> womans kitchen, stairs, mature women in clotheing, head spark plugs,
> mechaanical squids, Japaneseses assasins, tiem traval, volcanos, 
> a monstar, slow time at fastar speed, magic, wizzards, some dirty
> place, Kung Few, fighting, a lot of mess explodsians EVARYWHERE, 
> and just about anything else yuo can names!

...with greetings to Carnivore ;)
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: UML to Python/Java code generation

[Peter Dembinski]

"Grigoris Tsolakidis" <[EMAIL PROTECTED]> writes:

> There is tool to generate UML from Python Code...

The best is human brain.
-- 
http://mail.python.org/mailman/listinfo/python-list