Improvement: Step 2 tutorial and get_num_global_elements to mesh.hxx

[Vyp3er]

…mesh.hxx.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.28%. Comparing base (66cd94f) to head (34b8c2a).
⚠️ Report is 27 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2371   +/-   ##
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  Coverage   82.28%   82.28%           
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  Files         125      125           
  Lines       20701    20703    +2     
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+ Hits        17033    17035    +2     
  Misses       3668     3668           

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[lenaploetzke]

Thanks for your nice work :)

[lenaploetzke]

Thank you, i think we are nearly ready to merge here

[lenaploetzke]

I do like t8_step2 better but maybe mesh_step2 is even better? Then it is clear that we are not in the general folder? Sorry for the inconvenience. And you missed one in l. 61

[lenaploetzke]

Suggested change

	#include <mesh_handle/constructor_wrappers.hxx> /** Wrapper for basic Cmesh to mesh_handle conversions. */
	#include <mesh_handle/constructor_wrappers.hxx> /** Wrapper for basic cmesh to mesh_handle conversions. */

[lenaploetzke]

Suggested change

	#include <t8_schemes/t8_default/t8_default.hxx> /** default refinement scheme. */
	#include <t8_schemes/t8_default/t8_default.hxx> /** Default refinement scheme. */

[lenaploetzke]

Suggested change

	* See step1 for a detailed description.
	* See \ref tutorials/general/t8_step1_coarsemesh.cxx for a detailed description.

[lenaploetzke]

In general, we start template parameters with T. I used TMeshClass throughout the code.
Please also add a doxygen doc for this. You could also use the concept t8_mesh_handle::T8MeshType here (and include the concepts header.). I think its maybe cool to learn about the concept here. (also add a comment about the concept then.)

[lenaploetzke]

Suggested change

	t8_global_productionf (" [t8_step2] Hello, this is the step2 example of t8code using the mesh handle.\n");
	t8_global_productionf (" [t8_step2] Hello, this is step 2 of t8code's mesh handle tutorials.\n");

[lenaploetzke]

Suggested change

	t8_global_productionf (" [t8_step2] In this example we build our first uniform mesh and output it to vtu files.\n");
	t8_global_productionf (" [t8_step2] In this tutorial we build our first uniform mesh and output it to vtu files.\n");

[lenaploetzke]

Suggested change

	* We will put the Mesh in a separate scope here,
	* We will put the mesh in a separate scope here,

[lenaploetzke]

Suggested change

	* because it will destroy itself completely on its own when reaching the end of this scope.
	* because it will be destroyed automatically at the end of this scope. This is only needed because SC_CHECK_MPI checks for leftover references. Otherwise, it would be destroyed at the end of the main function.

I think we need a line break here, sorry

[lenaploetzke]

I think it would even be cleaner if we write using mesh_class= .... here and add the explanation:
The mesh class is templated so that further competences/features that are not needed by default can be added to it. This is explained in more detail in the further tutorials. In our case, the default mesh class is sufficient.