Added static asserts to fixed length header structures.

[Dimi1010]

The PR adds cpp11 static_assert statements after the declarations of fixed length structured used throughout Packet++ for encoding/decoding raw data.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.11%. Comparing base (d60c699) to head (0d6c2c9).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1693      +/-   ##
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- Coverage   83.11%   83.11%   -0.01%     
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  Files         277      277              
  Lines       48207    48207              
  Branches    10192     9932     -260     
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- Hits        40069    40068       -1     
  Misses       7243     7243              
- Partials      895      896       +1     

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[seladb]

@Dimi1010 why are these static asserts needed? 🤔

[Dimi1010]

@Dimi1010 why are these static asserts needed? 🤔

They aren't needed per se, but they provide compile time safety that the header structures are precisely the specified fixed length, as they will raise an error at compile time if not.

[seladb]

@Dimi1010 why are these static asserts needed? 🤔

They aren't needed per se, but they provide compile time safety that the header structures are precisely the specified fixed length, as they will raise an error at compile time if not.

I always wondered why static asserts are needed 🙂
If someone decides to change a struct, it's probably for a good reason and they'll need to update the static assert as well.
Is there any real purpose for it?

[Dimi1010]

I always wondered why static asserts are needed 🙂
If someone decides to change a struct, it's probably for a good reason and they'll need to update the static assert as well.
Is there any real purpose for it?

That is kinda the point. If you are changing the structs, it stops you by asking the question: "Do you really have a good reason to change it?". If you do, you change the assert too (and all the code that depends on the assert, hopefully).

My opinion in general about them is that it prevents accidental changes and also ensures that certain assumptions that the developers make about the code are correct, instead of only relying on the dev(and all other devs that work the same code) that the assumption holds.

It can also be used as a self documenting code. Without the assert, a person might not know that this struct is used in a way that needs it to be precisely N bytes long, unless they look through the code. There is the option of it being noted in documentation comments, but that is easier to forget to update than a static assert if making a change to the assumption.

[tigercosmos]

I think this change is helpful. It prevents people changing the struct layout accidently. I think asssertion and test are always useful.