Parameter

class mcalf.utils.collections.Parameter(name, value=None)

Bases: object

A named parameter with a optional value.

The value can be changed at any time and very basic operations can be queued and evaluated on demand.

Parameters:

• name (str) – Name of parameter.

• value (int or float, optional, default=None) – Value of parameter. Other types may work but not supported.

name

Name of parameter.

Type:

str

value

Value of parameter, without operations applied.

Type:

int or float

operations

List of operations to apply.

Type:

list

Raises:

• ValueError – The parameter is evaluated without a value.

• NotImplementedError – Operations which require parentheses are applied.

See also

Parameters

Collection of synced Parameter objects.

Notes

Basic operations can be applied to this object, i.e., +, -, * and /. The Parameter object must be the left-most entity in an expression. Expressions which require parentheses are not supported. The only types that are supported in expressions are Parameter, float and int. Any type should work as a value for Parameter (such as an array), however, only float and int are supported. See the examples for more details in how it works.

Examples

>>> Parameter('x')
'x'
>>> Parameter('x', 12)
'12'
>>> Parameter('x') + 1
'x+1'
>>> Parameter('x', 1) + 1
'x+1'
>>> a = Parameter('y') * 2
>>> a
'y*2'
>>> a.value = 5
>>> a == 10
True
>>> a.eval()
10
>>> (a * 10).eval()
100
>>> a * 10 + 1.5
'y*2*10+1.5'
>>> (a + 10) * 2
Traceback (most recent call last):
 ...
NotImplementedError: Parameter equations with brackets are not supported.

Attributes Summary

value_or_name

Returns its value if set, otherwise returns its name.

Methods Summary

apply_operation(op, other)	Apply an operation to the Parameter.
copy()	Return a copy of the parameter.
eval()	Evaluate the expression using the parameter's current value.
verify()	Enforce order of operations.

Attributes Documentation

value_or_name

Returns its value if set, otherwise returns its name.

Methods Documentation

apply_operation(op, other)

Apply an operation to the Parameter.

Parameters:

• op (str) – Operation symbol to apply. +, -, * or /.

• other (float or int) – Number on RHS.

Returns:

A copy of self with the operation added to the queue.

Return type:

obj

Notes

You should only use this method directly if a builtin Python operation is not otherwise implemented in this class, i.e., do a + 1 and not a.apply_operation('+', 1).

copy()

Return a copy of the parameter.

eval()

Evaluate the expression using the parameter’s current value.

verify()

Enforce order of operations.