# Section 6.7.2:
Assign Statement

Assignment is the only way of altering the value of a state component in Sather.

#### Concrete Syntax

assign statement = | (expression | (identifier, Colon_SY, [type specifier])),
| initialise ;

#### Abstract Syntax

Assign_Name = token
inv aname ==
aname = Assign ;
Predefined_Call ::
id : token
args : Feature
impl : Feature
rval : [Value_Expression] ;
inv mk_Predefined_Call(expid,args,imp,val) ==
expid = Assign
and len args = 2
and imp.imp = do_assign(args(1),args(2)
and val = nil
do_assign(loc : Address, val : ANY)

TO BE DONE

#### Static Semantics

The first argument must be a storage expression and the second a value expression.

#### Dynamic Semantics

The state component indicated by the evaluation of the first argument is changed to have the value given by the second argument.

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Comments or enquiries should be made to Keith Hopper. Page last modified: Wednesday, 31 May 2000. |