i've been reading some past posts and wanted to add some supplemental input on
this one and emphasize some key advantages to mirroring e4x templating syntax
in triple quoted strings. first currently beginning to work in as3 i highly
regard the progress the wg has made. es4 really has grown up into a very
structured (yet still almost uniquely flexible, extensible, and dynamic)
language in comparison to the tediousness of trying to scale up my js apps.
1. i have often missed string interpolation working in js although i have never
missed php's (and others?) multiline strings. i don't mind chalking that up to
inexperience and an unhealthy fondness for perl but i do feel string
interpolation is arguably second only to regex (which i also love) in perl's
historical success which both php and more effectlively ruby (with a syntax
like e4x) mimic.
2. as the poster below alluded to as3 already provides string interpolationde
facto via e4x. anywhere a string is expected i can substitute a XML literal
like <>Today is {new Date.toDateString()} and the time is {new
Date.toTimeString()}.</> ver batim. this does identify a few weaknesses
however:
first there is a great deal of overhead (creating the XML including the text
node as child XML, translating xml entities, recognizing the type context to
call toString(), forwarding toString() to the text node, and finally
translating the entities back) making it potentially inefficient for any long
running loop. the vm could optimize for this but why have to?
also it seems inconsistent to define the previous content with that facility
and have to redefine it normally:
//assuming xml was assigned the previous example now reassign its content
xml='The time is now '+new Date.toTimeString()+'.';
rather than the following possible employing string interpolation:
xml="""The time is now {new Date.toTimeString()}.""";
i won't contend that it's not largely syntactic sugar but the utility of string
interpolation in other languages especially server side is hard to argue. in
original responses to this post it was also alluded to that exactly three
characters must be escaped using e4x this way (<, {, and }, while others are
handled by the vm) which i will address next.
3. using triple quoted strings for string interpolation would not only negate
not having to escape new lines but any escape sequence syntax at all (including
for backslashes). literal delimiters could simply be included between braces
as traditional strings e.g.:
"""this {'example """is""" NOT\xA9 {utilitarian} per'} se"""
while i may not see the utility of literal new lines i heartily concur with not
having to remember to escape other characters (or recall yet another escape
sequence syntax) which gets especially messy instantiating a Regexp without
using literal syntax (for instance one that was built dynamically by
concatenating strings).
this seems be a low bar to implement given worst case it could be simply macro
processed to its current notation. i love working with es and look forward to
it becoming continually more enjoyable even if some features get deferred to
es5. i would also like to mention i emailed previously regarding a
function/method interceptor/sequence syntax but didn't consider until the
following day it would also benefit from proper tail calls which are already
being pursuing and would alleviate painfully deep stack traces from methods
with long inheritance chains.
~jon
----- Original Message ----
On 06/03/2008, jeff.ecmascript at tanasity.com
<jeff.ecmascript at tanasity.com> wrote:
> If I understand the motivation for triple quoted strings, it's to allow
> multiline strings with inverted commas and quotes within them, and to
> allow quotes and inverted commas within those substrings, all without
> requiring a continuation marker.
>
> PHP has a structure that's used for this sort of thing, which works
> quite well and is used when you have a large block of text tobe used as
> a string. As an example of when this is used, commonly, emails that are
> constructed in code use this technique.
The interesting thing is ECMAScript E4X extension already allows to
enter multiline strings like in:
var i = 10;
var str = <x>arbitrary
multiline text that can embed expression
{i * 2} references</x>.toString();
The triple quota proposal would introduce significantly less powerful
mechanism for embedding the strings.
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