Is the Safe-Bool Idiom Still Necessary in C 11?

The Obsolete Safe-Bool Idiom in C 11

In C 11, the necessity of the safe-bool idiom has been rendered obsolete by the introduction of explicit operator bool() const. According to the C standard Section 4 [conv] p3:

An expression e can be implicitly converted to a type T if and only if the declaration T t=e; is well-formed [...]

This means that an expression can be contextually converted to bool if the declaration bool t(e); is well-formed.

Certain language constructs require such implicit conversions, including:

• if, while, for
• binary logical operators & and ||
• logical negation operator !
• conditional operator ?:
• static_assert
• noexcept

Thus, with the availability of explicit conversion operators, it becomes unnecessary to resort to convoluted safe-bool implementations. This significantly simplifies and clarifies code, as explicit conversions provide clear and intentional type conversions compared to the implicit mechanisms of the safe-bool idiom.

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