Named elements of a table

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peceha
Posts: 111
Joined: Tue Dec 13, 2016 8:39 am
Location: Poland

Named elements of a table

Post by peceha »

That is something I just encountered and it made me wonder.
In the manual you can read:
You can access named elements of a table also in two ways:
b = a["name"]
b = a.name
Up to now, at the beginning of my script I had following table declaration:

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mapSettings	= {
	["minRmW"]		= 3,
	["minRmH"]		= 3,
	["maxRms"]		= 5,
	["rmChnc"]		= 80,
	["sparse"]			= 50,	
	["loops"]			= 50,	
	["rndDirTreshold"]	= 80
}
and I decided to replace it with this:

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mapSettings	= {
	minRmW			= 3,
	minRmH			= 3,
	maxRms			= 5,
	rmChnc			= 80,
	sparse			= 50,	
	loops			= 50,	
	rndDirTreshold	= 80
}


And now I had a lot of errors: "table field was not initialized" and it turned out that my old syntax was causing it:

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aLoc=bspSplit(0,0,#W,#H,mapSettings["maxRms"])
or from another table:

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colorReq.shadowOnOff=color["shadowOnOff"]
so I changed these entries to:

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mapSettings.maxRms
color.shadowOnOff
and it is working.

Have I misunderstood something here?

SamuraiCrow
Posts: 304
Joined: Fri May 15, 2015 5:15 pm
Location: Waterville, Minnesota USA

Re: Named elements of a table

Post by SamuraiCrow »

The quotes around the variable name mean that the name of the element is literally what's between the quotes, not the contents of the variable with that name.
I'm on registered MorphOS using FlowStudio.

peceha
Posts: 111
Joined: Tue Dec 13, 2016 8:39 am
Location: Poland

Re: Named elements of a table

Post by peceha »

Yes , I'm aware of this.
What I don,t understand is why my program gave me plenty errors about table fields not being initialized - all I did was a change from (example):

t["field"]=0
to
t.field=0

then everytime there was something like function(t["field"]) in my script , I had an error message, so had to change it to function(t.field)

t.field is the same as t["field"], right? - i just checked it and it seems to be right.

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Allanon
Posts: 629
Joined: Sun Feb 14, 2010 7:53 pm
Location: Italy
Contact:

Re: Named elements of a table

Post by Allanon »

Hi peceah,

looking to one of your example :

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mapSettings   = {
   ["minRmW"]      = 3,
   ["minRmH"]      = 3,
   ["maxRms"]      = 5,
   ["rmChnc"]      = 80,
   ["sparse"]         = 50,   
   ["loops"]         = 50,   
   ["rndDirTreshold"]   = 80
}
This is not the same of:

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mapSettings   = {
   minRmW         = 3,
   minRmH         = 3,
   maxRms         = 5,
   rmChnc         = 80,
   sparse         = 50,   
   loops         = 50,   
   rndDirTreshold   = 80
}
because there is no case distinction in table indexes, so for example:

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; SMALLER EXAMPLE
 test = {}
 test.Field1 = "Hello"  ; <- The real index stored is all in lowercase!
 DebugPrint(test.Field1)     ; This will work
 DebugPrint(test["field1"])  ; This will work
 DebugPrint(test["Field1"])  ; This will trow an error
If you want to maintain case distinction you have to store and retrieve items using ["..."] :

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 test = {}
 test["Field1"] = "Hello"
 DebugPrint(test["Field1"])  ; This will work
 DebugPrint(test.Field1)     ; This will trow an error
 DebugPrint(test["field1"])  ; This will trow an error
I hope this helps :)
----------------------------
[Allanon] Fabio Falcucci
AMC - Creative Development // Docs Site // Support Forum
Support me on Patreon for Hollywood libraries!

peceha
Posts: 111
Joined: Tue Dec 13, 2016 8:39 am
Location: Poland

Re: Named elements of a table

Post by peceha »

WOW :)

Thank You - that helped for sure !!!

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Allanon
Posts: 629
Joined: Sun Feb 14, 2010 7:53 pm
Location: Italy
Contact:

Re: Named elements of a table

Post by Allanon »

Great! :D
----------------------------
[Allanon] Fabio Falcucci
AMC - Creative Development // Docs Site // Support Forum
Support me on Patreon for Hollywood libraries!

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