Preserve extern keyword in function declarations

Include extern keyword in function declarations

Model Configuration Pane: Code Generation / Code Style

Description

Specify whether to include the extern keyword in function declarations in the generated code.

Note

The extern keyword is optional for functions with external linkage, such as model entry-point functions, global or scoped root-level Simulink^® functions, and referenced model functions. However, including the extern keyword in function declarations can enhance code readability.

Dependencies

When another model references this model, specify the same value that the parent model uses.

Settings

on (default) | off

Default: on

On

Include the extern keyword in function declarations in the generated code.

Off

Remove the extern keyword from function declarations in the generated code.

Examples

Control Generation of extern Keyword in Function Declarations

Compare the function declarations in the generated code when you set Preserve extern keyword in function declarations to different values.

Here is generated code that generated using the default Preserve extern keyword in function declarations value off:

/* Model entry point functions */
void CounterModel_initialize(void);
void CounterModel_step(void);

Here is the same code generated with Preserve extern keyword in function declarations set to on:

/* Model entry point functions */
extern void CounterModel_initialize(void);
extern void CounterModel_step(void);

The extern keyword explicitly indicates that the function has external linkage.

Recommended Settings

Application	Setting
Debugging	No impact
Traceability	No impact
Efficiency	No impact
Safety precaution	No impact

Programmatic Use

Parameter: PreserveExternInFcnDecls

Type: character vector

Value: 'on' | 'off'

Default: 'on'

Version History

Introduced in R2009b