Debugging and Internals Access

See also

neuron.nrn_dll()

Namespace Related

name_declared()

Syntax:

type = h.name_declared("name")

type = h.name_declared("name", 1)

type = h.name_declared("name", 2)

Description:

Return 0 if the name is not in the NEURON/HOC symbol table. The first form looks for names in the top level symbol table. The second form looks in the current object context. The last form also looks in the top level symbol table but is useful in Python to distinguish subtypes of variables which appear as doubles in HOC but internally are really not doubles and so cannot be pointed to by double*, eg. h.secondorder which is <type 'int'> or h.nseg which returns either TypeError: Section access unspecified or nseg  not a USERPROPERTY that can be pointed to

If the name exists return

2 if an objref

3 if a Section

4 if a strdef

5 if a scalar or double variable. (if second arg is not 2)

if second arg is 2

5 if a scalar double

6 if a double array

7 if an integer

8 if a section property

1 otherwise

Note

This function checks the NEURON/HOC symbol table; Python objects are handled separately.

To test if a simple name is a local variable in Python, use:

if 'soma' in locals():
    # do something

Checking against globals() and dir() are also often useful.

If the name is known in advance, use a try/except block and catch NameError and AttributeError:

try:
    h.soma.squiggle
except (NameError, AttributeError):
    print('Name does not exist')

Combining this with an eval can allow testing arbitrary names, but is potentially unsafe as it allows execution of arbitrary code.

---

symbols()

Name:

symbols --- type the names of HOC functions and variables

Syntax:

h.symbols()

Description:

Types a list of functions and variable names defined in HOC. Dimensions of arrays are also indicated.

Warning

No longer works. The nearest replacement is SymChooser() .

Object Related

object_id()

Syntax:

h.object_id(objref)

h.object_id(objref, 1)

Description:

Returns 0 if the object reference does not point to an object instance. (Otherwise returns the pointer cast to a double, not a very useful number, except that this is equal to the value returned by Python's hash function.)

If the second argument is 1, it returns the index of the object name. Returns -1 if the object is the NULLObject.

Example:

from neuron import h

a, b, c = h.List(), h.List(), h.Vector()

print(h.object_id(a))       # displays a double; equal to hash(a)
print(h.object_id(a, 1))    # 0 since a == h.List[0]
print(h.object_id(b, 1))    # 1 since b == h.List[1]
print(h.object_id(c, 1))    # 0 since c == h.Vector[0]

---

allobjectvars()

Syntax:

h.allobjectvars()

Description:

Prints all the HOC object references (objref variables) that have been declared along with the class type of the object they reference and the number of references. Objects created via Python and not assigned to a HOC objref

Example:

>>> h('objref foo')
1
>>> h.foo = h.Vector()
>>> h.allobjectvars()
obp hoc_obj_[0] -> NULL
obp hoc_obj_[1] -> NULL
obp foo[0] -> Vector[0] with 1 refs.
0.0
>>> banana = h.foo
>>> h.allobjectvars()
obp hoc_obj_[0] -> NULL
obp hoc_obj_[1] -> NULL
obp foo[0] -> Vector[0] with 2 refs.
0.0

---

allobjects()

Syntax:

h.allobjects()

h.allobjects("templatename")

nref = h.allobjects(objectref)

Description:

Prints the internal names of all class instances (objects) available from the interpreter along with the number of references to them.

With a templatename the list is restricted to objects of that class.

With an object variable, nothing is printed but the reference count is returned. The count is too large by one if the argument was of the form templatename[index] since a temporary reference is created while the object is on the stack during the call.

Example:

>>> v = h.Vector()
>>> foo = h.List()
>>> h.allobjects()
List[0] with 1 refs
Vector[0] with 1 refs
0.0
>>> h.allobjects('Vector')
Vector[0] with 1 refs
0.0
>>> h.allobjects(foo)
2.0

---

object_push()

Syntax:

h.object_push(objref)

Description:

Enter the context of the object referenced by objref. In this context you can directly access any variables or call any functions, even those not declared as public. Do not attempt to create any new symbol names! This function is generally used by the object itself to save its state in a session.

---

object_pop()

Syntax:

h.object_pop()

Description:

Pop the last object from an object_push() .

---

Miscellaneous

hoc_pointer_()

Syntax:

h.hoc_pointer_(&variable)

Description:

A function used by c and c++ implementations to request a pointer to the variable from its interpreter name. Not needed by or useful for the user; returns 1.0 on success.