A Suggestion for Python Dictionary/Class

[matt]

On Sat, 23 Dec 2000, William Djaja Tjokroaminata wrote:
> Hi all,
> 
> After using Python for a while, a have a wish for another type of
> dictionary.  If you ever used Tcl and Perl, you know that all Python, Tcl,
> and Perl basically provides three different fundamental data types:
> 
>     - scalar (Perl-speak) (which includes numbers and strings)
>     - list (or sequence in Python-speak)
>     - dictionary
> 
> But in Python, we have two different kinds of lists: lists and tuples.  I
> used Tcl and Perl before, so initially I was puzzled by why Python
> provides a 'read-only' list.  But it is fine.
> 
> I also use C and C++ a lot.  Their power and large-scale capabilities come
> from, among other things, the ability to write struct or class.  Among the
> three scripting languages, only Python provides the most natural form of
> struct/class like in C/C++/Java.  That's why I love Python so much; I can
> think in Python much like I think in C/C++/Java.
> 
> However, there is a fundamental difference with Python class.  The members
> are implemented using dictionary.  The danger with dictionary is, even
> though a key does not exist, we still can make an assignment to it.  When
> we make some typo, this can be hard to debug.  For example:
> 
>     class MyClass:
>         def __init__ (self):
>             self.member = 0
> 
>     myClass = MyClass ()
>     myClass.menber = 1    # This is a bug!
> 
>     print myClass.member  # Expected 0, but found 1



you mean Expected 1, but found 0

The only functionality I see you want is a spell checker of sorts?  maybe you
should include in your test units a print out of .__dict__ so you can see
easily that there are mistakes and that perhaps is the reason your test unit
failed.








> 
> In C/C++/Java, if a member does not exist and we try to access or assign
> it (because of some typo, perhaps), it will be caught by the compiler
> simply as syntax error.  Not so with Python class.
> 
> Therefore, is there any way for me to define a class, with some definite
> members just like in C/C++/Java, so that no new members can be defined?  I
> am trying to do it, but using some conventions, not using the Python
> language features.
> 
> Because Python provides a read-only list in terms of tuple, I think it
> will be nice if Python provides another class type with fixed members,
> just like a dictionary with read-only keys.  Any opinion, anyone?
> 
> Regards,
> 
> Bill
> -- 
> http://www.python.org/mailman/listinfo/python-list
-- 
Matt Halstead (PhD)
Research and development
VirtualSpectator
http://www.virtualspectator.com
ph 64-9-9136896