On 11/25/2015 03:18 PM, Sam Foster wrote: > Back in the day, in the dojotookit we used a combination of feature > detection and a require.js alike module system to build feature-specific > sources. So rather than magic comments with preprocessor meaning, you > got real conditionals in the code that were optimized away given a > feature-set profile at build-time. In practice this was mostly done at a > file/module level though - very similar to what Marcus proposes.
How is this different from a preprocessor? Regardless of the name, you're still adding conditionals that affect the result of a build based on certain configuration parameters. Sure, poorly-written preprocessor rules can result in unclear code with subtle bugs hidden within, but we're writing *Javascript*. That ship has already sailed. To be clear, we're really talking about two kinds of build-time configuration: line-based (preprocessor) and file-based (our build system). If people have run into limitations with the latter and feel the former would simplify their work, then I trust them on this, and my only recommendations would be in terms of what tool to use, not whether they should do this in the first place. In an ideal world, I'd prefer we just use something like the C preprocessor, since it's one of the best-known preprocessing languages, but as people rightly mention, this will break editors. Trying to edit preprocessed JS/XUL files in Thunderbird has always been fairly annoying. I'm less sympathetic to the fact that it would break our linter, but that's probably because I think linters are a bit silly to begin with; if you want good build-time checks that your code isn't totally broken, you should use a compiled language and compile with -Wall -Werror. :) That said, syntactically-significant comments are a bit ugly too. However, I don't think the ugliness outstrips their value. I definitely think we should use an existing preprocessor for this, provided we've thoroughly analyzed its strengths/weaknesses, and are confident that we won't end up relying on some project that gets abandoned in a year. I don't have a strong opinion on the specific tool we use, so long as it meets the requirements I listed above. Or we could use Rust's macro system. ;) - Jim _______________________________________________ dev-fxos mailing list [email protected] https://lists.mozilla.org/listinfo/dev-fxos
