Need some help how to distribute features between main.py and scripts on sd card

[liudr]

...Since you don’t have great control over when a module runs (at first import), it typically shouldn’t do anything else than define functions and classes, and possibly initialize some things. Any code that needs to run at a determined time should be inside those functions and classes.

I got it now. Thanks.

[pythoncoder]

No. Have the module with the logging function run

Code: Select all

import os

This forum is to support MicroPython: users assume a knowledge of Python. Your queries are elementary ones about the Python language. I would advise you to learn the language using Python on a PC with a book or online course.

[liudr]

No. Have the module with the logging function run

Code: Select all

import os

This forum is to support MicroPython: users assume a knowledge of Python. Your queries are elementary ones about the Python language. I would advise you to learn the language using Python on a PC with a book or online course.

That was the first thing in my mind. Unfortunately, I have not found evidence during my python book/doc reading that duplicate imports at the main and inside another module is not going to 1) waste memory by creating duplicate code/variables 2) cause hardware to lockup since the resource is a single SD card. I know that "if it works it must be OK". But that's not my programming motto. I'm going to do more investigation on the python import mechanism but meanwhile I'm seeking examples and pointers from more experienced python programmers on how to build a project in general.

In C, we use conditional pre-compiler directives to ensure the #include doesn't duplicate names in the final project when multiple source files rely on the same #include. It would otherwise result in some "first declared here" errors. I was able to improve my understanding of the compiling and linking process in C when I encountered the same issue, managing multiple source files as my projects grew longer. That was ~20 years ago. With Python, I was able to develop projects of sufficient complexity all inside a single script. This means my syntax is mostly solid enough. I am at the same point to develop my own modules and understand the impact of importing other modules. I can't visualize this process as I could with C. Maybe C is just less complex. Python seems more complex. What I figured out (may be wrong) is that if there is code in an imported module, the code runs in its own namespace, isolated from the importer. So I should enclose all code in functions so they only run AFTER import is over. It's taking more time than I anticipated for me to get the gist of the stuff. I'll try to keep things MicroPython-related instead of Python-related.

[pythoncoder]

Unused imports can easily creep into code, for example you might import time to test a function's execution time, then remove the test. So before releasing code I check for and remove unused imports. They waste RAM and make code that bit harder to follow.

As for crashing hardware

since the resource is a single SD card

I don't follow that reasoning. Normal Python code should never crash hardware, and this includes multiple or spurious imports. Serous abuse of uctypes or monkeying around with the inline assember aside, if MicroPython crashes the hardware you've probably found a language bug.

Python is quite unlike C in that respect.