Re: ! function

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From	"Christoph M. Becker" <cmbecker69@arcor.de>
Newsgroups	comp.lang.javascript
Subject	Re: ! function
Date	Tue, 19 May 2015 01:39:57 +0200
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Scott Sauyet wrote:

> Evertjan. wrote:
>
>> Christoph M. Becker wrote 
>>
>>> That's wrong.  According to ES 5.1 the line can't be parsed as
>>> FunctionDeclaration, because the Identifier is missing.  Actually, the
>>> code doesn't match any production, and as such is syntactically invalid.
>>
>> Quite, but that doesn't explain why
>>
>> !function(a){alert(a)}('ho');
>> +function(a){alert(a)}('ho');
>> -function(a){alert(a)}('ho');
>>
>> ... do not throw an error.
>>
>> "syntactically invalid" is just "according to the rules",
>> "throwing an error" is what should concern us in practice.
> 
> Ok, so we'll try to simplify a bit:

<snipped the story of Parry Parser and his colleagues>

A wonderful story – thanks for telling, Scott.  And a really fine
explanation of the interaction of parsers and scanners (aka
lexers/tokenizers).

Actually, I would like to see the story in a FAQ note.  Maybe chapter 4,
Function, should be augmented by a section about "Why is there an
operator before `function`?" (or similar), which explains the issue
shortly, and links to the full story.

Thoughts?

-- 
Christoph M. Becker

Thread

! function Andrew Poulos <ap_prog@hotmail.com> - 2015-05-07 20:15 +1000
  Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-07 13:04 +0200
  Re: ! function "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2015-05-07 05:02 -0700
  Re: ! function Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-05-07 12:27 -0300
    Re: ! function JJ <jj4public@vfemail.net> - 2015-05-08 00:09 +0700
    Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-07 21:07 +0200
      Re: ! function "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-05-07 21:31 +0200
        Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-07 22:20 +0200
          Re: ! function "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-05-07 23:27 +0200
            Re: ! function "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-05-08 00:26 +0200
              Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-08 11:00 +0200
                Re: ! function James Lewis <lewisje@gmail.com> - 2015-06-05 09:10 -0700
          Re: ! function Scott Sauyet <scott.sauyet@gmail.com> - 2015-05-18 13:31 -0700
            Re: ! function "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-05-19 01:39 +0200
              Re: ! function Scott Sauyet <scott.sauyet@gmail.com> - 2015-05-19 05:48 -0700
        Re: ! function Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-05-07 17:47 -0300
          Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-07 23:22 +0200
            Re: ! function Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-05-07 19:08 -0300
              Re: ! function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-05-08 12:08 +0200

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