multiple modules with the same name
johnjbarton at google.com
Mon Jan 27 15:14:30 PST 2014
On Mon, Jan 27, 2014 at 2:50 PM, Sam Tobin-Hochstadt
<samth at cs.indiana.edu>wrote:
> This is absolutely necessary for polyfilling.
> Imagine that some browser has an ok-but-not-complete implementation of
> the X library, but you want to use jQuery 17, which requires a better
> version. You need to be able to replace X with a polyfilled update to
> X, and then load jQuery on top of that.
> Note that this involves indirect access in the same library (jQuery)
> to two versions of X (the polyfill and the browser version), which is
> why I don't think Marius's worry is fixable without throwing out the
> baby with the bathwater.
Guy Bedford, based on experiences within the requirejs and commonjs worlds,
has a much better solution for these scenarios. (It's also similar to how
Your jQuery should depend upon the name X, but you Loader should map the
name X when loaded by jQuery to the new version in Loader.normalize(). The
table of name mappings can be configured at run time.
For example, if some other code depends on X at 1.6 and jQuery needs X at 1.7,
they each load exactly the version they need because the normalized module
names embed the version number.
This is the proper solution, not one based on overwriting the module
registry. To be sure, because of the overhead loading code on slow
networks these kinds of multi-version scenarios are less attractive in the
browser, but the fix is the adapt the code.
Guy's project has a bit more: https://github.com/guybedford/systemjs
> On Mon, Jan 27, 2014 at 5:45 PM, John Barton <johnjbarton at google.com>
> > What is the use case for allowing registration different modules under
> > same name? IMO should be an error.
> > jjb
> > On Mon, Jan 27, 2014 at 2:32 PM, David Herman <dherman at mozilla.com>
> >> On Jan 27, 2014, at 2:18 PM, Marius Gundersen <gundersen at gmail.com>
> >> > So then there would be two versions of the same module, and a module
> >> > could get access to both these modules at the same time. For example,
> >> > ModuleB, which depends on ModuleA is loaded and linked, and later
> ModuleA is
> >> > redefined, then ModuleC could depend on both ModuleB and ModueA, and
> >> > get (indirect) access to two versions of ModuleA. Is this problem
> >> > preventable?
> >> It's important to be able to modify module registration for things like
> >> polyfilling. But that doesn't mean it's something people should do in
> >> general. Note that Jason only gave you an answer in the context of the
> >> module loader semantics; he didn't say what will happen in the HTML
> >> semantics. In particular, we can make it an error for there to be two
> >> definitions of the same module name in the same HTML, a la:
> >> <script type="module" name="jquery" src="jquery1.js"></script>
> >> <script type="module" name="jquery" src="jquery2.js"></script>
> >> I'm inclined to call that an error, and require imperative modifications
> >> of existing module registrations to use imperative code.
> >> Dave
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