c.haslam

When an element of a Map is a Map

6 posts in this topic

I have found that:

Local $a[],$c[]
$a['cat'] = 'suki'
$c['ani'] = $a
MsgBox(0,'',VarGetType($c.ani.cat))

shows String, as expected. But I have discovered that

Local $a[],$c[]
$c['ani'] = $a
$a['cat'] = 'suki'
MsgBox(0,'',VarGetType($c.ani.cat))

shows Keyword.

I have found that VarGetType() returns Keyword when a non-existent key is encountered. For example

Local $a[]
$a['cat'] = 'suki'
MsgBox(0,'',VarGetType($a.cath))

shows Keyword because cath is not a keyword in $a.

Is the behavior in the second snippet by design?


...chris

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Thank you for telling me why VarGetType() returns Keyword. Your explanation is correct.

So I restate my question:

Local $a[],$c[]
$a['cat'] = 'suki'
$c['ani'] = $a
MsgBox(0,'',$c.ani.cat)

shows suki. But it shows nothing when lines 2 and 3 are reversed. Indeed,

Local $a[],$c[]
$c['ani'] = $a
$a['cat'] = 'suki'
MsgBox(0,'',$c.ani.cat=Null)

shows True. So the type of $c.ani.cat is Null: The addition of an element to $a is not seen by $c.

Is this by design?

 

 

 


...chris

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I'm speculating here, but I believe when you assign the map as an entity of the other map it is make by a copy of the original map, not some sort of reference to it.  Any updates made to the original map are not automatically copied to the entity-map.  Just a guess.

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It works the same way if you're using arrays as well, The array inside the array doesn't change when you change the embedded array.

Local $a[1],$c[1]
$c[0] = $a
$b = $c[0]
MsgBox(0,'Before $a is assigned a value',$b[0])
$a[0] = 'suki'
$c[0] = $a
$b = $c[0]
MsgBox(0,'After $a is assigned',$b[0])

You're only inserting what the array currently contains, not the array itself.


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Thanks. I had hoped that the dot notation indicated a reference.


...chris

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