MATLAB Object-Oriented Programming

Indexed Assignment

In this section...

“How Indexed Assignment Works” on page 17-31

“Indexed Assignment to Objects” on page 17-33

“Compound Indexed Assignments” on page 17-33

How Indexed Assignment Works

Object indexed assignments are in three forms — parentheses, braces, and dot-name:

A(I) = B

A{I} = B

A.name = B

Each of these statements results in a call by MATLAB to the subsasgn method of class A,

or a call to the built-in subsasgn function if the class of A does not implement a

subsasgn method.

MATLAB passes three arguments to subsasgn and requires subsasgn to return the

result of the assignment:

A = subsasgn(A,S,B)

The first argument, A, is the object being assigned the value in the third argument B.

The second argument is the indexing structure, substruct. S has two fields:

• S.type is a char vector containing '()', '{}', or '.' specifying the indexing type
  used.


• S.subs is a cell array or character array containing the actual indices or field name. A
  colon used as an index is passed in the cell array as the character ':'. Ranges
  specified using a colon (e.g., 2:5) are expanded to 2 3 4 5.

For example, the assignment statement:

A(2,3) = B;

generates a call to subsasgn:

A = subsasgn(A,S,B)

Indexed Assignment