arguments.md

Arguments

Only positional arguments (and sec=) are allowed in NEURON except for functions with no HOC equivalent that are handled separately.

Note: NEURON argument indices are always numbered from 1.

Check for the existence of an argument

Use ifarg(n) to check to see if there is an nth argument (the arguments are numbered from 1).

Many existing functions and methods currently do not check for too many arguments, however doing so is recommended as it indicates a probable user error.

Check the type of an argument

Relevant functions include:

• hoc_is_object_arg(n)
• hoc_is_pdouble_arg(n)
• hoc_is_str_arg(n)
• hoc_is_double_arg(n)

Get the value of an argument

Relevant functions include:

• hoc_obj_getarg(n)

  May want to combine this with nrnpy_ho2po if you know the argument is a PyObject; e.g.

   PyObject* obj = nrnpy_ho2po(*hoc_objgetarg(n))
  

• hoc_pgetarg(n) -- returns a double**

• gargstr(n)

• getarg(n) -- returns a double*. Python bools, ints, and floats are all valid inputs.

Note: attempting to get the wrong type of an argument displays a "bad stack access" message and a Python RuntimeError exception gets raised. If multiple types of arguments are possible, you must check the type of the argument first.