Pointers or References in API Design: When Should You Choose Which?

When to Use Pointers Instead of References in API Design

When defining function signatures in APIs, the choice between pointers and references can arise. While both can be used for passing arguments, their semantics differ, impacting clarity and potential issues.

Pointers vs. References: Syntax and Semantics

Pointers hold the memory address of a variable, representing a direct access to its value. References, on the other hand, are aliases for variables, providing a more indirect way of accessing and modifying them.

Factors to Consider When Deciding

The decision between using pointers or references in an API depends on several factors:

• Destructive vs. Non-Destructive Modification: Pointers inherently indicate that the passed variable can be modified (unless declared const), while references imply non-destructive operations by default.
• Null Values: Pointers can represent NULL values, while references cannot. If an API function can return or take NULL as an argument, a pointer should be used.
• Syntax Clarity: As highlighted in your example, pointers explicitly convey that a variable is passed destructively, enhancing code readability.

Generally Accepted Guidelines

Based on the factors above, the following guidelines can be followed:

• Use references when:

  • The passed variable should not be modified.
  • It is required for functions like operator , which explicitly rely on references.

• Use pointers when:

  • The passed variable needs to be modified.
  • NULL values are allowed or expected.
  • Enhanced code clarity is desired, indicating destructive operations.

Performance Considerations

Both pointers and references have minimal impact on performance. However, using pointers may introduce the overhead of checking for NULL values, while references cannot handle NULL values.

Conclusion

The choice between pointers and references in API design depends on the specific needs of the function. When clarity and explicit intent are important, pointers are preferred, especially for destructive operations. When ensuring argument validity is crucial, references offer simplicity and disallow NULL values. By understanding these guidelines, developers can create more robust and readable APIs.

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