destructuringBind

destructuringBind( 
l_variables 
l_expression 
[ g_body ] 
) 
=> g_result

Description

Enables you to bind value to variables in a list. The list of values is obtained by evaluating the l_expression. The destructuringBind macro then evaluates the g_body form.

destructuringBind does not check the correctness of l_variables.

Arguments

l_variables	A simple or a complex list. A complex list is a list that can include other lists. You can also use @optional, @key, and @rest in this list as a procedure or a function’s argument list.
l_expression	An expression that is evaluated and its result is assigned or bound to the corresponding variable in l_variables.
g_body	A sequence of one or more expressions.

Value Returned

g_result

The evaluated result of the last expression in g_body.

Examples

• Simple case:
  

  (destructuringBind (a b)  '(1 2) a+b )

  => 3

• Complex case: assume myBBox() returns ((0 0) (5 5))
  

  (destructuringBind (p1 p2) myBBox() 

  printf( "%L and %L points of a bounding box" p1 p2))

  (0 0) and (5 5) points of a bounding box

  => t

  (destructuringBind ((x1 y1) (x2 y2)) myBBox() 

  printf( "(%L %L) and (%L %L) points of a bounding box" x1 y1 x2 y2))

  (0 0) and (5 5) points of a bounding box

  => t

• Optional case
  

  (destructuringBind (a b @optional (c 1)) '(1 2 5) 

  printf("a=%L b=%L c=%L\n" a b c) a+b )

  a=1 b=2 c=5

  => 3

• Keyword case: assume myKeys() returns (100 ?key1 “Hello” ?key2 “World”)
  

  (destructuringBind (v1 @key key1 key2) myKeys() 

  printf( "Position value %L and key values %L %L" v1 k1 k2))

  Position value 100 and key values "Hello" "World"

  => t

Related Topics

Function and Program Structure

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