Feature request moose.Function should be able to accept variables names which are just not x0, x1, .. y0, y1

Created by: subhacom

Currently moose.Function variables must be named as x0, x1, ...., or y0, y1, etc.. I suggest that in addition to this, moose.Function should also accept any keyword prefixed with var_ or v_ (or something similar) as variables. This will make expressions more readable e.g. var_CAMKII over x0 representing CAMKII etc.

Reported by: dilawar

Created by: subhacom

This had been thought about and discussed before. Implementing this requires that either (1) Cinfo allows dynamic creation of named fields on any element, or (2) the entries in a FieldElement be allowed different names.

The constants can have arbitrary names because they are local to the Function element and a map can be used for translating the identifier to an entry in the 'c' field. However, this scheme poses a problem with ValueFinfos looked up from other objects (y) and DestFinfos filled in by other objects (x) because a connection needs to be setup using addMsg, a function which knows only the Cinfo of the class and is agnostic of the local variables of the elements it is connecting. So even if a map was used to translate between variable names and x/y index, the user will have to connect messages for them by index - which is even more cumbersome than just translating the formula by renaming all variables x{i}/y{i}.

You are welcome to further discuss and improve the implementation.

Original comment by: subhacom

Created by: dilawar

An attempt is being made on https://github.com/BhallaLab/moose-core/pull/367

Created by: dilawar

This is implemented in https://github.com/BhallaLab/moose-core/pull/390 . This is done at the Python level. In nutshell, a user is allowed to have an expression with arbitrarily named variables e.g. Ca+sin(Mg) instead of x0+sin(x1). Ca and Mg will be replaced by x0 and x1 whenever user connects these pool to the function. This is possible because the new parser based on exprtk (https://github.com/BhallaLab/moose-core/pull/387) allows dynamic lookup at runtime. More details are/will be at the PR.

Created by: dilawar

All tests are passing in https://github.com/BhallaLab/moose-core/pull/390 . When the PR is merged, this should be closed.