How to Jinja templates

Three files needed for Nek5000 are produced by Snek5000 through Jinja templates: <case name>.box, SIZE and makefile_usr.inc. As a Nek5000 user, you might want to understand how these important files are produced, so let us explain by diving into the code:

• These files are produced by the methods:

  • snek5000.output.base.Output.write_box() (which calls snek5000.operators.Operators.write_box()),

  • snek5000.output.base.Output.write_size() (which calls snek5000.operators.Operators.write_size()) and

  • snek5000.output.base.Output.write_makefile_usr().

• These methods are called in a method snek5000.output.base.Output.post_init_create_additional_source_files() which uses the class attributes template_box, template_size and template_makefile_usr. These attributes are defined in the solvers, for example for snek5000-tgv in the file snek5000_tgv.output:

  from snek5000.output.base import Output as OutputBase
  from snek5000.resources import get_base_templates
  
  box, makefile_usr, size = get_base_templates()
  
  
  class OutputTGV(OutputBase):
      template_box = box
      template_makefile_usr = makefile_usr
      template_size = size
  
      @property
      def makefile_usr_sources(self):
          """
          Sources for inclusion to makefile_usr.inc
          Dict[directory]  -> list of source files
          """
          return {}
  
      @classmethod
      def _set_info_solver_classes(cls, classes):
          """Set the classes for info_solver.classes.Output"""
          super()._set_info_solver_classes(classes)
  
          classes._set_child(
              "SpatialMeans",
              dict(
                  module_name="snek5000.output.spatial_means",
                  class_name="SpatialMeans",
              ),
          )
  
  
  Output = OutputTGV
  

  Note

  With this mechanism, the template files can be obtained from a simulation object with sim.output.template_box.filename.

• Some base template files are in the subpackage snek5000.resources. These files are general enough so that they can be used directly by most solvers (for example we saw that snek5000-tgv uses snek5000.resources.get_base_templates()). However, it is also possible to use other templates. For example, in snek5000-cbox, Jinja inheritance is used to extend the template for the SIZE file.