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How often do you show multiple screens open to a user at the same time? Even in desktop ERP type software you rarely ever show more than 3 to 4 screens open at

How often do you show multiple screens open to a user at the same time? Even in desktop ERP type software you rarely ever show more than 3 to 4 screens open at a time and how often do these screens all show the EXACT SAME data fields? How often do you show more than one screen open at a time in a mobile app? How often would you then need to display the same data field in multiple screens? I think the state management in mobile apps is extremely over engineered for a use case that rarely ever happens.

munificent 3y ago
Imagine you have a list of items. The list supports multiple selection. Elsewhere on the screen, you have a little box that shows the number of selected items, and the total order price of all of them. Elsewhere, there is an alert that shows up if the total order price is greater than some budget field. There is a button to order the selected items. The button should be disabled if the total price is greater than the budget. The budget amount is also a field that can be edited. First off, you have to decide where the selection itself is stored. Is whether or not an item is selected "model" state? Or "view model"? If the latter, is there a well defined place where that kind of data is stored or does it literally just list in the list UI element itself? If so, how do all of the other UI elements that need that state get it? Are they directly coupled to the list box? If a user selects "undo" does that change the selection? Is selecting or unselecting an item and undoable operation or not? If the back-end server sends an update that some item is no longer available, does the UI handle that appropriately? When the budget number changes, where does the validation logic to ensure the user chooses a reasonable number live? This is just a very simple example, but stuff like this comes up all the time and gets gnarly real fast.
- pkphilip 3y ago
  I have handled far more complex cases than this using desktop based GUI apps in a client-server model before the word AJAX etc was even invented. Example: dependent dropdowns or even tables with row-selection leading to more detailed views. The ability to display multiple views for the same data type at the same point - example: displaying orders from multiple clients simultaneously in two different sub-screens at the same time. Also, MVC as a concept has existed for decades. GUI controls have always had a concept of a "onChange" events and when it came to the code which fetches changes from the server, there were multiple ways of handling that - from using polling, to using message queues to using db triggers, from using plain socket calls etc. And also very sophisticated applications with literally 100s of screens - example: plane/hotel ticketing apps, stock trading applications, ERP/MRP software etc, have all existed for decades.
  - munificent 3y ago
    > And also very sophisticated applications with literally 100s of screens - example: plane/hotel ticketing apps, stock trading applications, ERP/MRP software etc, have all existed for decades. Yes, and many of those applications are being migrated from an event-based architecture to a reactive one because their authors find them easier to maintain.

munificent 3y ago

Imagine you have a list of items. The list supports multiple selection. Elsewhere on the screen, you have a little box that shows the number of selected items, and the total order price of all of them. Elsewhere, there is an alert that shows up if the total order price is greater than some budget field. There is a button to order the selected items. The button should be disabled if the total price is greater than the budget. The budget amount is also a field that can be edited. First off, you have to decide where the selection itself is stored. Is whether or not an item is selected "model" state? Or "view model"? If the latter, is there a well defined place where that kind of data is stored or does it literally just list in the list UI element itself? If so, how do all of the other UI elements that need that state get it? Are they directly coupled to the list box? If a user selects "undo" does that change the selection? Is selecting or unselecting an item and undoable operation or not? If the back-end server sends an update that some item is no longer available, does the UI handle that appropriately? When the budget number changes, where does the validation logic to ensure the user chooses a reasonable number live? This is just a very simple example, but stuff like this comes up all the time and gets gnarly real fast.

pkphilip 3y ago
I have handled far more complex cases than this using desktop based GUI apps in a client-server model before the word AJAX etc was even invented. Example: dependent dropdowns or even tables with row-selection leading to more detailed views. The ability to display multiple views for the same data type at the same point - example: displaying orders from multiple clients simultaneously in two different sub-screens at the same time. Also, MVC as a concept has existed for decades. GUI controls have always had a concept of a "onChange" events and when it came to the code which fetches changes from the server, there were multiple ways of handling that - from using polling, to using message queues to using db triggers, from using plain socket calls etc. And also very sophisticated applications with literally 100s of screens - example: plane/hotel ticketing apps, stock trading applications, ERP/MRP software etc, have all existed for decades.
- munificent 3y ago
  > And also very sophisticated applications with literally 100s of screens - example: plane/hotel ticketing apps, stock trading applications, ERP/MRP software etc, have all existed for decades. Yes, and many of those applications are being migrated from an event-based architecture to a reactive one because their authors find them easier to maintain.