Function Handle Limitations for Code Generation

When you use function handles in MATLAB^® code intended for code generation, adhere to the following restrictions:

 Do not use the same variable to reference different function handles

In some cases, using the same variable to reference different function handles causes a compile-time error. For example, this code does not compile:

function y = foo(p)
x = @plus;
if p
  x = @minus;
end
y = x(1, 2);

 Do not pass function handles to or from coder.ceval

You cannot pass function handles as inputs to or outputs from coder.ceval (MATLAB Coder). For example, suppose that f and str.f are function handles:

f = @sin;
str.x = pi;
str.f = f;

The following statements result in compilation errors:

coder.ceval('foo', @sin);
coder.ceval('foo', f);
coder.ceval('foo', str);

 Do not associate a function handle with an extrinsic function

You cannot create a function handle that references an extrinsic MATLAB function.

 Do not pass function handles to or from extrinsic functions

You cannot pass function handles to or from feval and other extrinsic MATLAB functions.

 Do not pass function handles to or from entry-point functions

You cannot pass function handles as inputs to or outputs from entry-point functions. For example, consider this function:

function x = plotFcn(fhandle, data)

assert(isa(fhandle,'function_handle') && isa(data,'double'));

plot(data, fhandle(data));
x = fhandle(data);

In this example, the function plotFcn receives a function handle and its data as inputs. plotFcn attempts to call the function referenced by the fhandle with the input data and plot the results. However, this code generates a compilation error. The error indicates that the function isa does not recognize 'function_handle' as a class name when called inside a MATLAB function to specify properties of inputs.

 Do not try to view function handles from the debugger

You cannot display or watch function handles from the debugger. The function handles appear as empty matrices.

 Do not use function handles for Simulink signals, parameters, or data store memory

You can use function handles in a MATLAB Function block. You cannot use function handles for Simulink^® signals, parameters, or data store memory.

Related Topics

• Use the coder.extrinsic Construct