On 30.08.2011 17:41, Rick Waldron wrote:
On Tue, Aug 30, 2011 at 3:39 AM, Dmitry A. Soshnikov
<[email protected] <mailto:[email protected]>> wrote:
OK, let's up the topic. Seems there are no technical issues in the
proposed thing -- we can simply either accept it or not. The
question is whether it's needed and sound proposal and the feature
to have in ECMAScript.
Some summarized features below:
+ Ability to get help of any built-in and any user-defined
function directly in runtime (in later case, authors should
provide the documentations though)
+ Auto-suggest and hints of parameters and their types when typing
function name in console.
+ Ability even to have sort of guards for types with issuing
warnings in case if types mismatch (sort of recent contract.coffee
projects and actually other langs, e.g. Haskell, Erlang, etc).
- Code size will be increased to store the doc string. This can be
optional in case of minimized scripts (lint tools can have option
"Remove doc-comments")
As an example I show a spec description for `parseInt` function:
15.1.2.2 parseInt (string , radix)
Let [[Documentation]] property of the `parseInt` function be the
following string:
"The parseInt function produces an integer value dictated by
interpretation of the contents of the string argument according to
the specified radix. Leading white space in string is ignored. If
radix is undefined or 0, it is assumed to be 10 except when the
number begins with the character pairs 0x or 0X, in which case a
radix of 16 is assumed. If radix is 16, number may also optionally
begin with the character pairs 0x or 0X."
...
x.x.xx help(F)
A built-in, global object function property named "help()" will no
doubt conflict with userland code
It's derived question, we may choose any name which fits well (though,
IMO `help` name isn't used much). The main thing I want to clarify at
this step, whether we need at all this thing in ES?
Since committee keeps silence, I'd like to consider it better as "Yes,
we need it and there is nothing to add", rather than "We don't need and
don't want even to discuss" (since there is no big sense in later,
because the functionality seems useful). However, we need to clarify how
*exactly* it's useful. Maybe using JS in console is so rare case and it
isn't required much. OTOH, era of client-side-only-JS is behind and JS
is also on server now. And from this viewpoint, in the console, it's the
best to get the help, hints for parameters and even type checking for
functions.
So, what should I do to apply the first meaning?
Dmitry.
When the `help` function is called on the F object, the following
steps are taken:
1. If [[Class]] of the function is not "Function" throw TypeError
2. Let doc be [[Documentation]] property of F
2.1 If doc is `undefined` return empty string
2.2. return String(doc)
It's a simplified version of course (moreover, Allen wanted to
eliminate [[Class]], so -- it's just an example).
Do we need this?
Dmitry.
On 09.08.2011 23:59, Dmitry A. Soshnikov wrote:
On 23.08.2011 20:54, Brendan Eich wrote:
A convenient notation for multiline documentation
comments, with convenient reflection (*not* via toString()
scraping!), would be a fine thing.
Yes, exactly this -- help(...) function, and also good
auto-complete of object methods helped me some time ago
formerly to learn Python very quickly just playing with it in
console. By the way, ECMAScript (who will take responsibility
to implement the ECMAScript -- ethanol implementation? :))
also needs some installation binaries with the console. And
yes -- with this great features for learning -- auto-complete
of methods (the best thing to investigate objects just
pressing `tab`) and help(...) function. I remember ES4 had/has
the REPL, why not ES5? Of course we have all those consoles
directly from the browsers (and also Node.js REPL), but it
could be useful. Anyway, it's another topic, just relatively
touches help(...) functions.
Some of the design dimensions:
0. Comment vs. string / quasiliteral?
1. function-only, or object literal too -- or any declaration?
I think functions are the main case, yes. Not sure about
literals, since there are open issues such as, "how to
document a property" (via descriptor field?)?
2. Before function, a la javadoc comments, or first thing
in body, a la the prologue directive idea?
That's said, if "before", then we should consider white-spaces
and newlines after the comment and before the function header
(though, as well as in the prologue). If "before", then tones
of old code written in javadoc will just work with the new
engine. OTOH, this means that the exact syntax of javadocs
will be standardized at the level of the spec (and it's a
sound thing -- people will have to write exactly e.g.
@property that the "doc-er" catch it correctly. OTOH again --
why not? -- to standardize common syntax of documenting
functions). However, the spec may not parse the exact content
of the comment but just save it as a string, regardless of
what is written insides.
A variant with "inside" is also good, underlines that the
comment is sort of a function's "property" (I like yours
simple "doc" name for that). Both variants are good, just
"outside" has the advantage that the old code will just hook
on it.
3. Reflected via function .doc property, a
Function.extractDocComment static method, or something
even more mirror-like/stratified?
Yes, both are fine, ".doc" is great. Perhaps, even global
binding help(...).
I'm not sure what is best, I lack experience programming
in languages with doc-comment or triple-quoted equivalents
(Python attached tests, e.g.). Comments (heh) welcome.
Thinking about 1, I would start with function-only.
Yes, this is the main case.
For 2 I'm inclined to say "in body" because it's too easy
to lose the "before" context during the life of a
function, compared to losing part of the body by accident.
At first glance there should be no issues with parsing in both
cases. We sure have to restrict that only the first multiline
comment from _above_ of a function is treated as doc-comment.
It will not touch any other upper-comments
// this one isn't caught
/*
and this one also
*/
/**
* but this is OK
*/
function foo() {}
console.log(foo.doc); // "but this is OK"
With the prologue -- there also directives' places should be
considered. I think the best place for them is under the
doc-comment.
function foo() {
"" My function """
"use strict";
}
Regarding 3, I bet Function.extractDocComment or a better
name wins, especially if the whole solution allows
monkey-patching a polyfill for downrev browsers that
support source recovery (not SpiderMonkey's decompiler).
Yes, maybe.
Dmitry.
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