insert data in python script

[DL Neil]

...

>> import preos
>> # pass name, Tc, Pc, omega
>> methane = preos.Molecule("methane", -82.59 + 273.15, 45.99, 0.011)
>> methane.print_params()

...

> my code preos in one file preos.py
> my commands are
> 
> alberto at HENDRIX ~/PREOS $ python3.5
> Python 3.5.2 (default, Oct  8 2019, 13:06:37)
> [GCC 5.4.0 20160609] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import preos
>>>> methane = Molecule("methane", -82.59 + 273.15, 45.99, 0.011)
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> NameError: name 'Molecule' is not defined


The first instruction (immediately above) imports the module preos.py. 
That works (no error message!).

The second instruction refers to a Python class called Molecule. That 
fails. The error message says that 'Molecule' is not defined.

Yet we can 'see' it. It *has* been defined! What is going on???

In this case, we need to tell Python that Molecule is part of the preos 
module. So back to your original code (top):

methane = preos.Molecule("methane", -82.59 + 273.15, 45.99, 0.011)


Please refer to earlier message. If Module were called from code in the 
preos.py file, then the "preos." prefix would not be necessary.

The formal term for this situation is "namespaces". Because Molecule is 
defined within the preos.py module's namespace we need to tell Python 
exactly where Molecule can be found. In the same way that we might say: 
if someone in Antarctica wants to see Alberto, (s)he will have to go to 
Italy to find him...


Don't hesitate to say if you think my reply is too complicated/advanced. 
People here are happy to help...
-- 
Regards =dn