Le 27/12/2012 06:32, Brendan Eich a écrit :
Mark S. Miller wrote:
Superstition aside, and once pre-ES5 browsers are not significant, the
only purpose of sloppy mode is for old code that must be kept running
without active maintenance.
That is a teleological statement -- you're talking about purpose,
designed intent, goal, "The Good (Life)".
Very philosophical, I dig it ;-). However, in reality as Dave said in
a recent message, the Law of Least Effort says people will forget to
write "use strict"; and we'll have sloppy mode code till the cows come
home.
The Law of Least Effort also brought us compile-to-JS languages.
Coffeescript still doesn't compile with "use strict"; by default [1],
but it seems open to it when all non-strict browsers will have died and
the perf issues are solved.
In the future, I expect:
* more usage of compile-to-JS languages
* all compile-to-JS languages to compile to strict mode by default
Interestingly, this would turn the result of the Law of Least Effort
from "some will forget" to "people won't forget".
Of course people will probably always write handwritten JS and some will
forget to put "use strict";, but I feel new non-strict code will
eventually become a rare exception asymptotically leading to, but never
reaching inexistence.
For any code being actively maintained, it
should move into strict mode.
Very hortatory, but the kids are alright and they don't all follow a
single "should". Between dissenters and LoLE or Law of Murphy ;-), I
bet your "should" will become an ineffectual nag over the next few years.
If, one fine day, virtually everyone does as in Perl and starts their
programs with "use strict'; (or "module {" with closing "} after), I
will raise a toast to you and others who helped teach that practice.
It's nowhere near a certainty, and "should" isn't "would" or "will".
I feel this will happen when compile-to-JS compile by default to strict
mode. Only years will tell.
Sloppy mode will become a relic only for code no one touches.
Perhaps, but not on a predictable schedule and not (if I'm right)
within the next few years, when we want ES6 adoption -- including new
syntax.
I sadly agree.
Finally, to connect to the first point, strict mode has some overhead
(LoLE works against it, people forget to type the directive). I know
developers who do not use strict mode, but who will rapidly adopt rest
and default parameters, destructuring in general, and other new forms.
This adoption of ES6 is partly subjective, distributed over time and
(head-)space. It should not be yoked to strict mode adoption.
+1
Yoking the two multiplies the likelihood of adoption to get a smaller
product. That's why I favor implicit strict mode only for bodies of
new head syntaxes, starting with module as Dave proposed.
I'm ok wtih class opting its body into strict mode, although did we
decide that one way or the other? I forget.
I don't know, but I'd be in favor of implicit strict in classes. Moving
code to module and classes would be the gradual move to strict mode Mark
talks about.
If people notice perf issues against equivalent not-in-module/class
code, they'll report it. Hopefully, that'll be an incentive enough for
implementors to make strict mode at least as fast as sloppy mode.
David
[1] https://github.com/jashkenas/coffee-script/pull/2337
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