BUG-Variable not available in either the 'gui_instance' or '__main__' module when they are in fact in __main__

[gbritoda]

Description and How to reproduce

My understanding is that you need to have your callbacks and variables in the same scope as where you instantiate the Gui object, OR at __main__ (the file which was called)

But I don't think that's happening. I am trying to instantiate the Gui in a separate file and have the callbacks and variables. imported to another main.py file, alongside the instantiated Gui object (the reason I need to do this is part of a bigger issue which I wont touch now).

Here's a mockup of the code in 3 different files:

callbacks_and_vars.py

from taipy.gui import notify

def test_callback(state):
    notify(state, "I", "Button was pressed")

TEST_VAR = "This is a test text"

gui_instance.py

from taipy.gui import Gui

GUI_OBJ = Gui()

main.py

from gui_instance import GUI_OBJ
from callbacks_and_vars import test_callback, TEST_VAR

GUI_OBJ.add_pages(
    {
        "/":"<|button|label={TEST_VAR}|on_action=test_callback|>"
    }
)
print(__name__)
GUI_OBJ.run()

I get the following output:

__main__
[2024-04-30 11:10:54][Taipy][INFO]  * Server starting on http://127.0.0.1:5000
WARNING:root:
--- 3 warning(s) were found for page '/'  ---
 - Warning 1: Variable 'TEST_VAR' is not available in either the 'gui_instance' or '__main__' modules.
 - Warning 2: Variable 'TEST_VAR' is not defined (in expression '{TEST_VAR}'):
'types.SimpleNamespace' object has no attribute 'TEST_VAR'
 - Warning 3: button.on_action: test_callback is not a function.
----------------------------------------------

I am particularly suspicious of the warning that says - Warning 1: Variable 'TEST_VAR' is not available in either the 'gui_instance' or '__main__' modules., because that's not the case, everything is in the __main__ module.

Expected behavior
The GUI file should have the variables in its cope as they are present in __main__

Screenshots

Runtime environment
Please specify relevant indications.

• Taipy version: 3.1.0
• OS: Windows 11 but running on WSL

Acceptance Criteria

• Ensure new code is unit tested, and check code coverage is at least 90%
• Create related issue in taipy-doc for documentation and Release Notes if relevant

[FabienLelaquais]

One way of dealing with that would be to add a setting for the variable scope in the Gui constructor.

[dinhlongviolin1]

Hi, for this use case of yours it is important to place everything next to each other so Taipy GUI can handle things properly. If you want to do multi pages, you can visit this section on the doc. Let me know if you have any further question

[gbritoda]

Hi @dinhlongviolin1 , this unfortunately doesn't apply for my use case. The code here is a simplification.

The reason I am structuring it like this is because I need to declare the Gui instance before some callbacks due to me running a bunch of different callbacks in different threads that need the state variable, thus needing the Gui instance as their parameter.

I needed that back in Taipy 2.4.0, dont know if there's a better way to do this, I based that from https://docs.taipy.io/en/release-2.1/manuals/gui/callbacks/#long-running-callbacks-in-a-thread

In short, it's something like this:

gui_instance.py

from taipy.gui import Gui

GUI_OBJ = Gui()

callbacks_and_vars.py

from gui_instance import GUI_OBJ
from taipy.gui import notify, get_state_id, invoke_callback

def _test_loop(state):
     # (...) do stuff with state like state.refresh in a loop for a while
    notify(state, "I", "Button was pressed")

def start_test_loop(state_id:str):
    invoke_callback(GUI_OBJ, state_id, _test_loop, args=[])

def test_callback(state):
     loop_thread = threading.Thread(target=start_test_loop, args=[get_state_id(state), daemon=True)
     loop_thread.start()
     # (...) do other things in parallel

TEST_VAR = "This is a test text"

main.py

from gui_instance import GUI_OBJ
from callbacks_and_vars import test_callback, TEST_VAR

GUI_OBJ.add_pages(
    {
        "/":"<|button|label={TEST_VAR}|on_action=test_callback|>"
    }
)
print(__name__)
GUI_OBJ.run()

This is the only way of structuring the files that I can see that avoids a circular import of GUI_OBJ

[gbritoda]

But I am importing everything into main.py, so that should work no? Especially because the message says either at __main__ or at where the Gui was declared

[dinhlongviolin1]

Thanks for getting back to me. The thing that I don't really understand is why you need the Gui instance declare before everything else. The state within the Gui won't be there until the application is up. You can declare it and it will be executed later on. If you really want this structure, what I will suggest you trying out is this structure. Let me know if it helps.

gui_instance.py

from taipy.gui import Gui

GUI_OBJ = Gui()

callbacks_and_vars.py

from gui_instance import GUI_OBJ
from taipy.gui import notify, get_state_id, invoke_callback, Markdown

def _test_loop(state):
     # (...) do stuff with state like state.refresh in a loop for a while
    notify(state, "I", "Button was pressed")

def start_test_loop(state_id:str):
    invoke_callback(GUI_OBJ, state_id, _test_loop, args=[])

def test_callback(state):
     loop_thread = threading.Thread(target=start_test_loop, args=[get_state_id(state), daemon=True)
     loop_thread.start()
     # (...) do other things in parallel

TEST_VAR = "This is a test text"

page = Markdown("<|button|label={TEST_VAR}|on_action=test_callback|>")

main.py

from gui_instance import GUI_OBJ
from callbacks_and_vars import page as page1

GUI_OBJ.add_page("page1", page1)
print(__name__)
GUI_OBJ.run()

[gbritoda]

Hi, I need it for the start_test_loop, it needs the GUI already instantiated.

This structure of yours is the same as the code as I just wrote in regards to variable scope isn't it? Everything is imported to __main__, but it won't work as everything needs to be in gui_instance, which is where GUI_OBJ is created.

The issue is that the error message that I get is - Warning 1: Variable 'TEST_VAR' is not available in either the 'gui_instance' or '__main__' modules., so that code should indeed work

[dinhlongviolin1]

If you do it as I did and create a Markdown instance as a page, it will work since it will consider that a moudle of its own. We call that one Page Scopes. Please give it a try.

[gbritoda]

will do! Thanks

[gbritoda]

Wow, it worked! Thank you so much for this. Will try it on my bigger application and see how it goes but I am now much more optmist.

[gbritoda]

@dinhlongviolin1 in that case, however, do all pages need to be declared in the same file? Or can they be declared in different files then imported into main.py? And what about the callbacks, they need to be where exactly? Because youre not importing them into main.py so I imagine it needs to be within the same scope as the Markdown?

[dinhlongviolin1]

Yes, your assumption is correct. All the variables + functions should be included within the same file/module as the Markdown instance. You can add multiple Markdown instances in different files to create a multi page application.

[dinhlongviolin1]

I will close the issue. If you have any problem, you can open a new issue or contact me directly through nguyen.dinh.long@taipy.io

[gbritoda]

Hi @dinhlongviolin1, but I think the issue is still not addressed.

Sure we have made the code work for my case but this looks more of a workaround. The warning message states that the variable should be in either gui_instance or in __main__, but the warning does not go away even when the variable is explicitly imported into __main__. So I'd argue that either the message is wrong or the behaviour is not expected. Wouldn't you agree?