Should You Use 'class' or 'typename' for Template Parameters?

Preference for 'class' or 'typename' in Template Parameters

When defining C template parameters, the choice between 'class' and 'typename' has been a subject of debate. This article explores the historical and technical considerations behind each keyword and discusses the potential reasons for preferring one over the other.

Historically, 'class' was used solely to specify types in templates to avoid introducing a new keyword. However, concerns arose that this overloading of 'class' caused confusion.

To address this ambiguity, the C committee introduced 'typename' as a new keyword specifically for specifying template types. The intent was to reduce confusion and provide a clearer understanding of the code's structure.

Today, both 'class' and 'typename' remain valid options for declaring template types. Aside from one specific case prior to C 17, they are generally interchangeable.

Some developers prefer 'typename' due to its dedicated purpose as a type specifier, providing greater clarity in the code. Others prefer 'class' out of habit or because it aligns better with their personal coding style. Ultimately, the choice between the two is a matter of individual preference.

It's worth noting that in the case of template template parameters (a type parameter that itself takes a template argument), 'class' was required before C 17. This was not a matter of preference but rather a requirement of the language. However, with C 17, both 'typename' and 'class' are accepted in this context as well.

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