questions.part #2

Ype Kingma ykingma at accessforall.nl
Wed Aug 8 00:18:59 CEST 2001


Dear reader,

whats_really_hot wrote:
> 
> This is the second post of mine. First, I would like to thank all u that
> responded to first post. Here I repeat some of the questions of my first
> post, because they were not properly answered or cause I didn't get straight
> answers.
>  In the first post u answered me that in Unix based platforms "cat" command
> starts the creation of a module. OK, now I go on with some more queries.
> 
On Unix I'd prefer to use vi over cat. Others use other editors like emacs,
or the editor in the Python development environment. But this subject is
off topic here.

> 1. When we type "dir()" in the interactive command line prompt get among all
> the others the module "__name__" which really tell us the name of the module
> that we are . But now we are in the interactive command line prompt, which
> is a module with the name "__main__". Now, my question is, why isn't
> __name__ = __main__? (Why isn't __name__ substituted by __main__?
>

This is simply a difference between interactive interpreter and the
'main python program' interpreter. The difference is not specified
by the language, it is just that these environments are not completely
the same: any python interpretation may start with some variables predefined.

> Sorry for repeating this question but I didn't really get a clear answer.
> 
Even the docs are bit terse about this.

> 2. What is the difference between "!=" and "<>" (which really mean
> "different")?
> 
I think only their origins are different: != comes from C, <> comes
from Pascal (who remembers Jensen and Wirth nowadays?).
In python they are equivalent, but it is possible that one of them 
is more favoured.

> 3. Are the built-in tools (such as "len", "sort" etc) maintained in a folder
> into the Python directory, so as I can access and edit them?
> 
They are implemented as functions in the implementation language,
currently C or Java. You can access them by extracting the sources
during python installation. In case you need the precise names of the 
equivalent functions, just ask here.

> 4.   What is the difference between "%d" and "%i" (which really point
> integer values)?
> 
Pass, my C usage is too far in the past. See the docs on the % operator.

> 5. What does it mean that Python is a "high-level language" and other
> languages, such as C, are low-level?
> 
In python you don't need to declare variables and a variable can be set to 
a reference to a value of any type.
When the parser does not detect syntax error in Python, everything is executed
until an uncaught exception occurs. Execution of a declaration or import has the
effect of adding name(s) to the namespace used by the interpreter.
Other statements change the references/values of the names in the applicable
namespace.

> Sorry for the simplicity of some of the above questions, but are crucial for
> me for the full understanding of Python.
> 
> Thanks again for ur attention and immediate responds.

My pleasure.

> 
> Mail me: whats_really_hot at hotmail.com
By request. Please see the newsgroup for more answers.

Good luck,
Ype

-- 
email at xs4all.nl



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