Inconsistent comma requirements

[Mark Waddingham]

On 2017-06-26 01:42, Monte Goulding via use-livecode wrote:
>> On 25 Jun 2017, at 1:37 am, Richard Gaskin via use-livecode 
>> <use-livecode at lists.runrev.com> wrote:
>> 
>> How many of you have never before known that commas are optional 
>> between definition arguments?
> 
> I have seen it before in user scripts but never used it myself. It’s
> one of those things you discover (like when {} could be used
> interchangeably with []) that you quickly realise you should never
> rely on so you forget pretty quickly ;-)

It is a HyperCard or SuperCard script compatibility thing I believe...

The ability to not have commas in the parameter declaration list does no 
real harm, although as a couple of people have pointed out means error 
detection in that specific case is less 'strong' so is probably best 
avoided for that reason, if no other.

> FWIW it actually wouldn’t be _that_ hard to add the ability to specify
> some syntactic sugar to your handlers and have the parser ignore said
> sugar:
> 
> e.g:
> 
> command Foo “with” pBar
> 
> end Foo
> 
> Foo with pBar
> 
> However this is somewhat less than and conflicts with the open
> language concept so it’s probably best not to consider it too
> seriously.

That suggestion is essentially the same as Richard's - whilst it is 
certainly an idea it means that errors in syntax can't be detected 
except at runtime (as you can have multiple handlers processed in the 
message path, and they can change dynamically). Also, in the case of 
just passing through 'keywords' as string literals you are moving 
parsing into the command handler - which means that parsing is then on 
the onus of the script writer, which means just making more work for 
scripts for what is probably of little benefit.

There's also an issue in that you can't really use any connecting words 
which are used to form expressions:

   doSomething dA and dB and dC

There's no way to know (with the 'ignore connectives' idea) how to 
process this - dA and dB (and all combinations) is a valid boolean 
expression. So in this case I might mean a command taking two parameters 
(ignoring 'and' in the first or second case), or one taking one 
parameter (dA and dB and dC).

Warmest Regards,

Mark.

-- 
Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
LiveCode: Everyone can create apps