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0 pointsWalterBright11mo ago0 comments

The example of a comptime parameter to a function is a template, whether you call it that or not :-/ A function template is a function with compile time parameters.

The irony here is back in the 2000's, many programmers were put off by C++ templates, and found them to be confusing. Myself included. But when I (belatedly) realized that function templates were functions with compile time parameters, I had an epiphany:

Don't call them templates! Call them functions with compile time parameters. The people who were confused by templates understood that immediately. Then later, after realizing that they had been using templates all along, became comfortable with templates.

BTW, I wholeheartedly agree that it is better to have a small set of features that can do the same thing as a larger set of features. But I'm not seeing how comptime is accomplishing that.

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pron11mo ago

> But I'm not seeing how comptime is accomplishing that.

Because Zig does the work of C++'s templates, macros, conditional compilation, constexprs, and concepts with one relatively simple feature.

WalterBrightOP11mo ago

From the article:

    fn print(comptime T: type, value: T) void {

That's a template. In D it looks like:

    void print(T)(T value) {

which is also a template.

pcwalton11mo ago

I think another way to put it is that the fact that Zig reuses the keyword "comptime" to denote type-level parameters and to denote compile-time evaluation doesn't mean that there's only one feature. There are still two features (templates and CTFE), just two features that happen to use the same keyword.

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