Python modules

Steve Hayes hayesstw at telkomsa.net
Mon Nov 10 07:58:16 CET 2014


On Mon, 10 Nov 2014 16:12:07 +1100, Ben Finney <ben+python at benfinney.id.au>
wrote:

>Steve Hayes <hayesstw at telkomsa.net> writes:
>
>> I have a book on Python that advocates dividing programs into modules,
>> and importing them when needed.
>
>Which book is this? (This is not essential to your question, but it
>might help to gauge your broader learning environment.)

Cunningham, Katie. 2014. Teach yourself Python in 24 hours.
               Indianapolis: Sams.
               ISBN: 978-0-672-33687-4
                   For Python 2.7.5

>> I can understand doing that in a compiled language, where different
>> modules can be imported from all sorts of places when the program is
>> compiled.
>
>Python is a compiled language; when you run a Python program a necessary
>step is to compile the Python source to a bytecode for actual execution.
>
>Usually, the compilation step is done dynamically; but (barring
>contrived examples) it is always done prior to running the program.
>
>> But I understand that Python is an interpreted language
>
>The two are not mutually exclusive. The Python interpreter works with
>compiled Python code, it does not execute the source directly.
>
>> If I wrote a program in Python like that, and wanted to run it on
>> another computer, how would it find all the modules to import at
>> run-time, unless I copied the whole directory structure over to the
>> other computer?
>
>That's the idea, yes. You need to distinguish between:
>
>* The standard library: installed along with the Python interpreter when
>  you install that, and available on the default module search path.
>
>* Third-party modules: installed using your package manager (ideally by
>  the operating system package manager), again to a location already
>  part of the default module search path on your system.
>
>* Modules specific to the application you're writing: Keep these in a
>  known hierarchy, and use the distribution tools to package them to
>  keep them together when distributing to oher machines.
>
>Use abolute import for standard library and third-party modules. Use
>relative import for application-private modules.
>
>This ensures your aplication's private modules don't conflict with
>current or future names of modules from the standard library or third
>parties.

So if I want to run it on another computer, where do I look for the compiled
executable program to copy?


-- 
Steve Hayes from Tshwane, South Africa
Web:  http://www.khanya.org.za/stevesig.htm
Blog: http://khanya.wordpress.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk



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