Problem replace item list

[Tnn]

i,

a strange thing …

I explain, because doing REPLACE of an ITEM in the lstTrattSell list at position 1,

it also changes the item to the same position in the list lstDbDefault ???

so instead it works ...

why???

the first block does not have to do the same thing ???

[TimAI2]

That is what you are asking the blocks to do :)

In your first image you are replacing the entire list of lists in lstDbDefault with what is in lstTrattSell, because "position 1" is the first "make a list" block

In your second image, you are also replacing everything in the the first list of lists

Please explain what you want to achieve, then we can help you sort your blocks out

(it may also help if you make a decision on which AppInventor you are going to use, if AI2 then ask here, if Thunkable / other, then ask on their forums)

[Tnn]

I do not understand, because if I modify an item in lstTrattSel, which is a separate list, 

it also changes the item in the lstDbDefault list ???

[TimAI2]

I am not seeing an issue ?

[Tnn]

So there's a problem somewhere ...

because I running the code instead I have this:

[TimAI2]

Do it like this:

Seems there is a pass through from the first list by selecting an item that is a list

Creating a new list from the list items fixes this. Confusing, but there is some logic in there somewhere.

[ABG]

This looks like a good place to use the copy list block.

It is for when you want to make a new list with a copy

of another list, and for each of the 2 lists

to have lives of their own, one independent of the other.

ABG

[Tnn]

yes, I had already used this solution ...

oh well ... I am perplexed!

[Taifun]

I explain, because doing REPLACE of an ITEM in the lstTrattSell list at position 1,
it also changes the item to the same position in the list lstDbDefault ???

this behavior is called call-by-reference

see also https://en.wikipedia.org/wiki/Evaluation_strategy

to copy a list use the copy list block

Taifun 

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Trying to push the limits of App Inventor! Snippets, Tutorials and Extensions from Pura Vida Apps by Taifun.