Array referencing

[stam]

Now I'm confused lol

@trevix: Heh - my post was a little dense!

Perhaps a much shorter way to explain the 'dynamic path' feature is this:

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get tArray[A][B][C][D][E]
put tValue into tArray[A][B][C][D][E]

Is equivalent to:

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put [ A, B, C, D, E ] into tPath
get tArray[tPath]
put tValue into tArray[tPath]

I understand the first example of course, or at least I think it do.
It should create an array

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tPath[A] = empty
tPath[A][B] = empty
tPath[A][B][C] = empty
tPath[A][B][C][D] = empty
tPath[A][B][C][D][E] = tValue

What find confusing is the new syntax... does this create a nested array or are these just keys of the array - from my limited understanding, this would produce

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tPath[1] = A
tPath[2] = B
tPath[3] = C
tPath[4] = D
tPath[5] = E

Admittedly for preferences anything would be fine, but if I've understood the new syntax correctly you define the value top level keys (unless you pass an array I suppose) - is that right?

[Klaus]

Sometimes this kind of stuff works, if you DO it.
At least worth a try...

[stam]

I will - but I’m on call for 7 consecutive days, and the chance of getting close to my Mac, let alone play with code is limited to weekend after next...
At least I have my phone to keep me occupied between cases
But I can only go on what I’ve seen posted.

Are you saying that

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put [ A, B, C, D, E ] into tPath
get tArray[tPath]
put tValue into tArray[tPath]

Creates an array where only

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tArray[A][B][C][D][E] = tValue

and all other keys like tArray [A][ B] are empty?

Not being argumentative, genuinely trying to understand the new syntax.

[LCMark]

@stam: So:

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put [ A, B, C, D, E ] into tPath
get tArray[tPath]
put tValue into tArray[tPath]

Does indeed create an array where:

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tArray[A][B][C][D][E] = tValue

However, the other keys are not empty - they contain the nested arrays. If you assume that A-E (which I was just using as placeholders for arbitrary expressions) are the strings A-E, then the resulting array (in JSON) is:

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{ "A": { "B": { "C": { "D": { "E": <value in tValue> } } } } }

Remember that the value of an array key is only a single value - its either a scalar (string etc.), or another array - they can't hold both an array and a scalar (for want of a better way to put it).

The array subscript operator is nested - ones further to the right refer to keys 'deeper' in the array hierarchy. The 'dynamic' feature I mentioned on this thread is just a dynamic way to do what you can do statically in script.

The [ A, B, C, ] (and { A: B, ... }) syntax is just the new shorthand for array literals which is more compact than using lots of puts to build them.

P.S. If my posts / response is still not clear / hard to understand - if you try and explain what you don't quite get, then I'll try again

[stam]

Thank you for talking the time to explain Mark!

I was thinking of this like comma-separated elements rather than nested arrays… still seems a bit strange but I think I get it, thank you.

Stam

[mwieder]

@LCMark-

!!! That's brilliant !!!
I take it both new array index syntax forms are LC10+ only.

[LCMark]

@mwieder: Array literalts [] and {} syntax is new in LC10, dynamic paths have been around a while (I'm tempted to say since before 6.0 but I'm not 100% sure).

[rkriesel]

@mwieder: Array literalts [] and {} syntax is new in LC10, dynamic paths have been around a while (I'm tempted to say since before 6.0 but I'm not 100% sure).

@LCMark: Comments for bug id 7166 indicate dynamic paths appeared first in release 3.5.

Dynamic paths are a great feature, but there's still no mention of them in the user guide or dictionary (or have I just missed it?).

-- Dick