Are Exception Specifiers Still Relevant in Modern C ?

Should I Incorporate Exception Specifiers in C ?

Exception specifiers in C allow functions to indicate whether they may throw exceptions, such as:

<code class="cpp">void foo() throw(); // guaranteed not to throw an exception
void bar() throw(int); // may throw an exception of type int
void baz() throw(...); // may throw an exception of some unspecified type</code>

While these specifiers can convey intent, their practical use is questionable due to several factors:

Limitations in Enforcement

Compilers do not strictly enforce exception specifiers, reducing their effectiveness. Ideal behavior would involve compile errors for violating specifications, but this is not guaranteed.

Severe Punishment for Violations

If a function violates an exception specifier, the standard behavior is to terminate the program. This harsh response may not be desirable in all cases.

Inconsistent Treatment in Development Environments

Some development environments, such as VS.Net, treat throw(X) as throw(...), undermining adherence to the standard.

Arguments Against Exception Specifiers

In addition to the above concerns, several arguments advocate against the use of exception specifiers:

• Compatibility with Templates: Exception specifications can hinder the development of template code due to unpredictable exception behaviors.
• Prohibition of Extensibility: Specifying expected exceptions may limit the evolution of code over time.
• Compatibility with Legacy Code: Dealing with legacy code makes it difficult to predict possible exceptions, potentially leading to program termination.
• Focus on Error Handling: Emphasis should be placed on returning common errors and reserving exceptions for exceptional scenarios.

When Exception Specifiers May Be Useful

Despite the general recommendation against using exception specifiers, they can still be beneficial when:

• A library throws only its own exceptions, allowing for clear intent specification. However, this use case is rare in practice.

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