# Technical training MetOs@UiO Day 4: modular based coding
- Lesson [webpage](https://sunnivin.github.io/lesson-modular-type-along/)

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## :shaved_ice: Icebreaker question

My favorite programming language(s) is(are):
- python :snake: +13
- C++ :desktop_computer: +
- Javascript
- R
- Matlab
- Logo :)

## Questions to answer before the exercise:
1. What does “modular code development” mean for you?
- Answer:
- Having different scripts with functions that are reusable in different contexts +3
- To have a pipeline where data preparation, data processing and data visualization are spilt into seperate parts and can interface with each other.+
- Breaking up the problem in smaller pieces, and solving them individually +8
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2. What best practices can you recommend to arrive at well structured, modular code in your favorite programming language?
- Answer: Write enough comments on the functions you're creating (also about units etc)
- Start looking at a good example. Like the CTSM code. :) :) :) :) :) :) :) :) :) :) :) :):)
- Never use "temporal" solutions (temporary)
- Read about language standards +1
- Use an IDE (helped me a lot!) +2 (tip: PyCharm, Spyder) [List for python](https://www.google.com/aclk?sa=L&ai=DChcSEwjqyqrwi5vuAhUDtrIKHT9yCnkYABAAGgJscg&ae=2&sig=AOD64_2z2gJiwX3dMcK6EY9IcQzPbHISpw&q&adurl&ved=2ahUKEwj99aHwi5vuAhXxs4sKHUDPB7wQ0Qx6BAgDEAE)
- properly naming the variables +2 (obs: F77 standard! e.g. AATM, BATM, CATM)
- Remember that you will probably need to publish your code if you publish your research (helps to motivate :P (even your analysis software))
3. What do you know now about programming that you wish somebody told you earlier?
- Answer: You should always read the docs before asking questions. +2
- functions -> modules-> packages or libraries
- How to use a debugger [Code Refinery on debugging](https://youtu.be/a6zCiqX3058) +2
- Knowing that it is possible to run single lines instead of the whole script. (e.g. F5 vs F9 in Spyder)
- I wish someone had shown me the quick-hack vs. proper development graph!
- Think about how the different part of the code should interface with each other.
- Using a commandline argument parser.
- How to write tests
- Comment your code, always, extensively, clearly, **in English** +2
- Bad : // J'ai eu ce bout de code de la part de Fred, ça marche+
- Good : // Implementation of the pseudo-code in [Smith, 2007], Section 3.2, DOI:XXXXX
4. Do you design a new code project on paper before coding? Discuss the pros and cons.
- Answer: I sometimes write down a basic outline before I start coding.
- Sometimes, and it's always leads to better structured code :)
- Only if I am having a lot of doubt about the structure. I.e. if it's difficult to design
- No, but it sounds like a good idea
- I tell/force my students to do it, and they look at me like I'm a mad man (Luc) ROTFL
- Always if I'd to add to a larger code base.+1
5. Do you build your code top-down or bottom-up? Discuss the pros and cons.
- Answer:
- bottom-up
- mostly bottom up I think
- (1) Think about the structure (2) build the frame (3) fill up the walls
6. Would you prefer your code to be 2x slower if it was easier to read it?
- Depends on how long the code is running
- Yes, unless being slower makes it useless in some cases (e.g., weather forecast). +1 ++

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## Questions to be answered after the exercise:
- Do we still agree on the points written before the exercise? Revisit the points written above.

#### Further improvements (we will see this tomorrow)
- Are there some obvious features we have not (yet) done in the file `improvements.py`?
- If you are the supervisor of the student, how would you suggest that the student performs incremental improvements? (Sneak-peak of the subject of tomorrow which is **code reviews**).

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# Questions:
- How is "source code" actually defined? In Python for example, what would you put in the "packagename" and what in the "packagename/lib" folder?
- All program code is source code. Libraries are source code which is meant to be resused by other code afterwards. They consist of generalised functions, classes and so on. Regarding an example in python: If you are developing an analysis, there will be functions, like calculation of volume mixing ratios or temperature conversions, that you will need several different places. This functions would go to lib. Your actual analysis, would be build of several such functions.
- What does 'pure' mean in fortran
- Nice answer for a longer explanation [here](https://stackoverflow.com/questions/30264729/proper-use-of-the-pure-keyword-fortran)

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