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espressomd / espresso

The ESPResSo package
https://espressomd.org
GNU General Public License v3.0
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Remove global variables #2628

Open jngrad opened 5 years ago

jngrad commented 5 years ago

Global variables make code difficult to read and maintain. Tracking their origin is an annoyance, and name collision with local variables is always a risk. Should we consider prefixing global variables with g_, just like we prefix class member variables with m_ and enum values with their enum name? Or enclosing them in namespaces, like enum values from enum classes?

Here is one special example, hiding in the global scope of some LB code: https://github.com/espressomd/espresso/blob/b25c0148bde7908af926e6360198ac7532c6688a/src/core/grid_based_algorithms/lbgpu.cpp#L115

Documentation is also affected by this situation, because Doxygen doesn't have a reliable scope resolution mechanism (Doxygen incorrectly states this variable is referenced by 380 functions).

fweik commented 5 years ago

The one you mention is also a linking hazard. In general most should also be static.

jngrad commented 5 years ago

Other example: there is a global variable energy: https://github.com/espressomd/espresso/blob/182020aa5d0c09c4283b3b55db7439038e98a7a2/src/core/energy.hpp#L38 which can easily be shadowed in functions calculating energies, forcing the use of alternative variable names, like _energy, eng, ret.

Removing globals is also an option: e416e7e528bf3da75, d47a73138a, 34b8821dd3f682, fab58ca37ae, 6b56534

jngrad commented 4 years ago

Progress report:

jngrad commented 3 years ago

Progress report: