Static Typing in Python

[Premshree Pillai]

How do I force static typing in Python?

-Premshree Pillai

=====
-Premshree
[http://www.qiksearch.com/]

_______________ _______________ _______________ _______________ ____________
Yahoo! India Insurance Special: Be informed on the best policies, services, tools and more.
Go to: http://in.insurance.yahoo.com/licspecial/index.html

[John Roth]

"Premshree Pillai" <pr************ **@yahoo.co.in> wrote in message
news:ma******** *************** *************** @python.org...

How do I force static typing in Python?
By using another language. Try Java.

John Roth
-Premshree Pillai

=====
-Premshree

[Peter Maas]

Premshree Pillai schrieb:

How do I force static typing in Python?

You have to enforce it by code instead of declaration, i.e. you
have to do runtime type checking. This could be done e.g. within
a class:

class doesTypeCheckin g:
def __init__self():
aString = ""
aFloat = 0.0

def __setAttr__(sel f, attr, value):
if type(self.__dic t__[attr] != type(value):
raise ValueError, "Type mismatch for attribute %s\n" % attr

Similar code could be used to check parameters of a function/
method.

Have looked at pychecker? It's not part of the python
distribution but it could help here.

Mit freundlichen Gruessen,

Peter Maas

--
-------------------------------------------------------------------
Peter Maas, M+R Infosysteme, D-52070 Aachen, Hubert-Wienen-Str. 24
Tel [phone] Fax [phone] eMail pe********@mplu sr.de
-------------------------------------------------------------------

[Peter Maas]

Peter Maas schrieb:

class doesTypeCheckin g:
def __init__self():

Correction:
def __init__(self):

--
-------------------------------------------------------------------
Peter Maas, M+R Infosysteme, D-52070 Aachen, Hubert-Wienen-Str. 24
Tel [phone] Fax [phone] eMail pe********@mplu sr.de
-------------------------------------------------------------------

[Jacek Generowicz]

Peter Maas <fp********@net scape.net> writes:

Premshree Pillai schrieb:

How do I force static typing in Python?

You have to enforce it by code instead of declaration, i.e. you
have to do runtime type checking.

Just what do you understand "static typing" to mean ?

[Peter Maas]

Peter Maas schrieb:

class doesTypeCheckin g:
def __init__(self):
aString = ""
aFloat = 0.0

sorry, I was too hasty. Here is the tested code:

class doesTypeCheckin g:
def __init__(self):
self.__dict__["aString"] = ""
self.__dict__["aFloat"] = 0.0

def __setattr__(sel f, attr, value):
if type(self.__dic t__[attr]) != type(value):
raise ValueError, "Type mismatch for attribute %s\n" % attr

Mit freundlichen Gruessen,

Peter Maas

--
-------------------------------------------------------------------
Peter Maas, M+R Infosysteme, D-52070 Aachen, Hubert-Wienen-Str. 24
Tel [phone] Fax [phone] eMail pe********@mplu sr.de
-------------------------------------------------------------------

[Dang Griffith]

On 12 Mar 2004 13:56:53 +0100, Jacek Generowicz
<ja************ **@cern.ch> wrote:

Peter Maas <fp********@net scape.net> writes:

Premshree Pillai schrieb:

> How do I force static typing in Python?

You have to enforce it by code instead of declaration, i.e. you
have to do runtime type checking.

Just what do you understand "static typing" to mean ?

Doesn't that usually mean typing with a high noise-to-signal ratio?
Lots of punctuation and such.
;-)
--dang

[Jacek Generowicz]

Jacek Generowicz <ja************ **@cern.ch> writes:

Peter Maas <fp********@net scape.net> writes:

Premshree Pillai schrieb:

How do I force static typing in Python?

You have to enforce it by code instead of declaration, i.e. you
have to do runtime type checking.

Just what do you understand "static typing" to mean ?

I ask because I am prepared to accept that you have a different
working definition of "static typing" from mine, but people who
actually want static typing typically want it because they think it
gives them the following advantages:

a) type errors caught at compile time,

b) faster program exectution.

The code you showed:

class doesTypeCheckin g:
def __init__(self):
self.__dict__["aString"] = ""
self.__dict__["aFloat"] = 0.0

def __setattr__(sel f, attr, value):
if type(self.__dic t__[attr]) != type(value):
raise ValueError, "Type mismatch for attribute %s\n" % attr

will catch no type errors at compile time, and will slow down
execution, so I suspect that Premshree will be disapponinted with it.
(BTW, my definition of "static typing" is "type checking is done at
compile time" ... your example really looks like dynamic typing to
me ... albeit with some restrictions on attribute types.)
Premshree: Python is dynamically typed. There is no way to enforce
static typing. There is something called "pychecker" which
might be of some help to you. Why do you think that you
want static typing in Python ?

[Jacek Generowicz]

Dang Griffith <no*****@noemai l4u.com> writes:

On 12 Mar 2004 13:56:53 +0100, Jacek Generowicz
<ja************ **@cern.ch> wrote:

Just what do you understand "static typing" to mean ?

Doesn't that usually mean typing with a high noise-to-signal ratio?

What, you mean like this:

std::list<std:: pair<int, std::string> > l;
l.push_back(std ::pair<int, std::string>(1, "hello"));

as opposed to

l = [(1, 'hello')]

?

I like your definition :-)

[Dang Griffith]

On Sat, 13 Mar 2004 07:07:50 +0000 (GMT), Premshree Pillai
<pr************ **@yahoo.co.in> wrote:

--- Jacek Generowicz <ja************ **@cern.ch>
Yes, I am aware that Python is dynamically typed, and
so is Perl, right? In Perl, we have the "use strict
vars" pragma to force variable declaration. Is there
something like it in Python?
No, but you can use pychecker to get similar results.
Don't you think forced variable declaration is an
important requirement in a language?

Not really. Forced variable initialization is what's important.
Unlike C, et al, and Perl, variables don't have a default
initial value. If you try reference a variable that hasn't been
initialized ("bound to a value", in python lingo), python raises a
NameError exception.

--dang
p.s.
I know technically Perl initializes to 'undef', but it's magically
treated as 0 or an empty string, depending on context, so the
effect is much the same.