Hi, I would like to know the different usage of "is a list" and "is list empty".
It seems there are circumstances where "is list empty" cannot be used when checking if a list exists.
Thank you.
Hi, I would like to know the different usage of "is a list" and "is list empty".
It seems there are circumstances where "is list empty" cannot be used when checking if a list exists.
Thank you.
from the documentation http://ai2.appinventor.mit.edu/reference/blocks/lists.html
If thing is a list, returns true; otherwise, returns false.
If list has no items, returns true; otherwise, returns false.
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by Taifun.
To simplify it -
is a list
is used to check if the given value, (a variable or something from a database or any other input) is a list or not and returns -
is list empty
is used to check if the given value, (a variable or something from a database or any other input) is a an empty list or not and returns -
OR maybe I just complicated it...
Here is an experiment for you.
Apply the block "is list empty" to a blank text block.
What is the result?
Apply the block "is list empty" to a variable holding blank text value.
What is the result?
My experience is that even if a variable is not a list, "is a list" can still return true. Is this correct?
No, but how about you show us an example of your experience.
What does an empty list mean? There is a tag but no value(" ")?
Sorry, please ignore my earlier question. I think I confused list with storage in TinyDB or TinyWebDB.
This is what I meant
Thanks to all.
Hi Anke, I tried experimenting with the list components again and I couldn't find anything which is in contradiction to your statement. Thank you🤣
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