What you're observing has nothing to do with :modules. It appears there's
been a minor DCE regression wrt. trivial programs. If you remove :modules
the exact same thing will manifest.
The regression is in fact minor though as it's precisely the same thing
that happens the moment you use a ClojureScript data literal.
David
On Wed, Feb 18, 2015 at 9:47 AM, Edwin Park <edwin.p...@gmail.com> wrote:
> > I noticed that if I remove the module for com.foo.common, the code in
> there gets included in cljs_base.js in the compiler temporary output, but
> there is no dead code elimination performed there. This may be expected, it
> just means that I need to declare all my code in modules if I want it
> minified.
> >
> >
> >
> > This is not true. You do not need to declare all your code in modules.
> It is the presence of ^:export that prevents DCE.
>
> I just want to clarify what I'm seeing. Here is the compiler config with
> the com.foo.common module removed and the ':depends-on #{:common}' lines
> removed:
>
> {:optimizations :advanced
> :output-dir "resources/assets/js/out"
> :modules {
> :landing
> {:output-to
> "resources/assets/js/landing.js"
> :entries #{com.foo.landing}
> }
> :editor
> {:output-to
> "resources/assets/js/editor.js"
> :entries #{com.foo.editor}
> }}}
>
> And here are my cljs files with ^:export on all the functions:
>
> src/cljs/com/foo/common.cljs:
>
> (ns com.foo.common)
> (defn ^:export blah [x]
> (str "[" x "]"))
>
>
> src/cljs/com/foo/landing.cljs:
>
> (ns com.foo.landing
> (:require [com.foo.common :refer (blah)]))
> (defn ^:export land [x]
> (str "landing:" (blah x)))
>
>
> src/cljs/com/foo/editor.cljs:
>
> (ns com.foo.editor
> (:require [com.foo.common :refer (blah)]))
> (defn ^:export edit [x]
> (str "editing:" (blah x)))
>
>
> When I compile, the landing and editor js files are generated:
>
> resources/assets/js/landing.js:
>
> da("com.foo.landing.land", function(a) {
> return[B("landing:"), B(ge(a))].join("");
> });
>
>
> resources/assets/js/editor.js:
>
> da("com.foo.editor.edit", function(a) {
> return[B("editing:"), B(ge(a))].join("");
> });
>
>
> There is also a resources/assets/js/out/cljs_base.js file generated in the
> compiler temporary output with the code from com.foo.common appended at the
> bottom of a lot of other stuff:
>
> ...4700+ lines...
> function ge(a) {
> return[B("["), B(a), B("]")].join("");
> }
> da("com.foo.common.blah", ge);
>
>
> The issue is the 4700+ lines of unused preamble in the cljs_base.js. I
> guess I was expecting the cljs-base file to simply contain the referenced
> com.foo.common code and DCE to eliminate the rest of it so I'd have a
> minimized file with just the code I need that I could load up into the
> browser.
>
>
> > Also, about the explicit module dependencies declarations: it seems like
> it should be possible to automatically generate these by analyzing the
> namespace metadata. Is there a reason to force this to be explicitly
> declared instead?
> >
> >
> > As far as I can tell both Thomas Heller & Google have come to the
> conclusion that only explicit dependencies work reliably. I didn't bother
> exploring alternatives since I didn't think I would do any better :)
>
> I'm curious about this. Thomas, can you comment on what the issues are?
> I'm thinking if I scan all the namespaces listed in :entries and collect
> all of their requires, I should be able to automatically generate the
> :depends-on for all cljs dependencies. I can understand how arbitrary js/
> dependencies may need to be explicitly declared, but any cljs dependencies
> should be knowable by inspecting the requires metadata on a given namespace.
>
> Thanks,
> Edwin
>
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