A bit confused by B.3.2 - Web Legacy Compatibility for Block-Level Function Declarations

John Lenz concavelenz at gmail.com
Thu Jun 5 09:51:57 PDT 2014

Is there any place that has some concrete examples of the different cases
we are trying support with this section (and whether the function is block
scoped or not in each case)?

On Thu, Jun 5, 2014 at 9:45 AM, Allen Wirfs-Brock <allen at wirfs-brock.com>

> On Jun 5, 2014, at 8:14 AM, John Lenz <concavelenz at gmail.com> wrote:
> On Wed, Jun 4, 2014 at 8:52 PM, Allen Wirfs-Brock <allen at wirfs-brock.com>
> wrote:
>> We don’t want to leave the meaning of function declarations in blocks
>> completely unspecified, as in ES1-5 as we; know there are legacy
>> compatibility requirements for them.  So, we need to have some semantics
>> for them.  The easiest way to provide any semantics is to simply use the
>>  same  block scoping semantics that is used in strict mode (slight
>> augmented to  over the legacy intersection semantics).  That actually
>> limits the refactoring hazard because as long as you have no code that
>> depends upon the legacy intersection there is no difference between the
>> function in block strict and sloppy semantics.
> It is the slightly augmented part that seems to be the problem here.  It
> is (1) very confusing and (2) creating the refactoring hazard: introducing
> a function of the same name in a different block breaks the scoping.  I
> would be happy to be misunderstanding that section.
> Nobody likes the augmented part, but it’s what is necessary for web legacy
> compatibility.
> Allen
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