Merge branch 'feature/getparam-default-template-arg' into 'master'

[parameters] default to string in getParam

See merge request !3669

CHANGELOG.md

@@ -22,6 +22,7 @@ be evaluated with the function values provided in the same order as the names wh
 - __PDESolver__: The LinearPDESolver/NewtonSolver now has an `apply` method that returns a bool (true if converged) instead of throwing an exception
 - __Freeflow Nonisothermal__: An issue with the compositional heat flux's upwinding calculations has been fixed
 - __Compositional Staggered__: The staggered discretization method has been updated to fix inconsistencies in handling density when evaluating diffusive boundary fluxes. In addition, a total mass balance is now always considered, rather than a total mole balance.
+- __Parameters__: The template argument for `getParam` and `getParamFromGroup` now defaults to `std::string`, such that for string parameters one can simply write `const auto param = getParam("MyParam");`
 
 ### Immediate interface changes not allowing/requiring a deprecation period:
 

dumux/common/parameters.hh

@@ -135,7 +135,7 @@ private:
  * \note \code auto endTime = getParam<double>("TimeManager.TEnd"); \endcode
  * \note Once this has been called the first time, you cannot modify the parameter tree anymore
  */
-template<typename T, typename... Args>
+template<typename T = std::string, typename... Args>
 T getParam(Args&&... args)
 { return Parameters::getTree().template get<T>(std::forward<Args>(args)... ); }
 
@@ -145,7 +145,7 @@ T getParam(Args&&... args)
  * \note \code  auto endTime = getParamFromGroup<double>("FreeFlow", "TimeManager.TEnd"); \endcode
  * \note Once this has been called the first time, you cannot modify the parameter tree anymore
  */
-template<typename T, typename... Args>
+template<typename T = std::string, typename... Args>
 T getParamFromGroup(Args&&... args)
 { return Parameters::getTree().template getFromGroup<T>(std::forward<Args>(args)... ); }