DEFINITE ASSIGNMENT

Other Expressions

16.1.16

Note that if

a

 is

V

 and

V

 is not definitely assigned before a compound assign 

ment such as

a

&=

b

, then a compile time error will necessarily occur. The rules

stated above include the disjunct  

a

 is

V

  so that

V

 will be considered to have been

definitely assigned at later points in the code. Including the disjunct  

a

 is

V

  does

not affect the binary decision as to whether a program is acceptable or will result

in a compile time error, but it affects

how many

 different points in the code may

be regarded as erroneous, and so in practice it can improve the quality of error

reporting.

16.1.14   Other Assignment Expressions

Suppose that an assignment expression

a

=

b

,

a

+=

b

,

a

 =

b

,

a

*=

b

,

a

/=

b

,

a

%=

b

,

a

<<=

b

,

a

>>=

b

,

a

>>>=

b

,

a

&=

b

,

a

|=

b

, or

a

^=

b

 is not boolean valued.

V

 is definitely assigned after the assignment expression iff either

a

 is

V

 or

V

 is

definitely assigned after

b

.

V

 is definitely assigned before

a

 iff

V

 is definitely assigned before the assign 

ment expression.

V

 is definitely assigned before

b

 iff

V

 is definitely assigned after

a

.

16.1.15   Operators

++

 and

V

 is definitely assigned after a preincrement, predecrement, postincrement, or

postdecrement expression iff either the operand expression is

V

 or

V

 is defi 

nitely assigned after the operand expression.

V

 is definitely assigned before the operand expression iff

V

 is definitely

assigned before the preincrement, predecrement, postincrement, or postdecre 

ment expression.

16.1.16   Other Expressions

If an expression is not boolean valued and is not a conditional operator expression

or assignment expression, the following rules apply:

If the expression has no subexpressions,

V

 is definitely assigned after the

expression iff

V

 is definitely assigned before the expression. This case applies

to literals, simple names,

this

,

super

, and

null

.

If the expression has subexpressions,

V

 is definitely assigned after the expres 

sion iff

V

 is definitely assigned after its rightmost immediate subexpression.

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