An Item is a single number (numeric Item) or string (literal Item).
It is used to represent calculus elements like : -3 ; +4.5 ; 296 ; 10³⁺⁸ ; (-8)²
and like : 'A' ; 'CD' ; 'x' ; 'b²' ; '-y³'
but not elements like : -5x², which should be represented by a Product of two Items (-5 and 'x²') or by a Monomial.
An Item embeds a Value.
It is an Exponented and its exponent is an Exponented itself, so it allows more complicated objects like 4^(x^2)
Possible args for __init__() :
None | Number | String | Item | (sign,value,exponent) | (sign,number|letter|Value) | 0-degree Monomial | Value
Fields :
value_inside : access to the Value embedded in the Item
raw_value : (read-only) access to value_inside.raw_value
is_out_striked : turn this boolean to True to have an out striked Item
force_display_sign_once : this boolean is used to force the display of a '+' sign in certain cases, but only once
unit : contains the unit of the Item (it should be merged with Value's unit field...)
Debugging info :
Doc for dev: Core Objects
Doc for dev: Monomial
Doc for dev: Product