Sharing data among MATLAB GUIs: Part 2

In Part 1 of the series, I have shown that how data can be shared between the guis by writing sub-functions in the gui to take over the responsibility. Even though the idea is simple, the actual implementation takes some skills and understanding of how MATLAB guis work.

Often time, you will see the use of global variables proposed as a quick and easy fix to the problem. If the design of the application is simple, I can see why it may be the preferred approach. However, the main issue I have with the use of global variables is its awkward use.

When you use global variables, you are forced to assign/read data to/from global variables instead of push/pull data. Why does it matter, you may wonder. Well, it is awkward. When you have two guis running at the same time, the user expects that the action performed in one gui should be sufficient to complete the data sharing, rather than interacting with two guis. For example, in the example I gave in Part 1, depending on which button the user clicks, the data will either be pulled or pushed to the target gui and displayed in the text box. If you were to use global variable, you will need to first save the string in a global variable and then load the string from the global variable in the target gui, which requires two actions from the user. Isn't that awkward for data sharing? That's just for two guis, if you have five guis, you will have to cycle through all five of them to have the most up-to-date version of the data in all five of the guis.

Not only more actions is required from the user, the order of the actions is also important. If the order is not followed properly, the results in the gui may not be what's expected. For example, if you read from the global variable in the target gui before assigning updated value to the global variable in the source gui, then the target gui has the outdated values.

Finally, if you wish to expand the existing application or combine it with other guis, there may be conflicts as to how the global variables are used. I can't imagine how much of a pain that is going to be (Really, I haven't done it that way, so I have no idea).

The above are just my opinions on why using global variable is not the appropriate mean to address the data sharing among MATLAB guis. That said, I am not an expert, so if anyone thinks I am talking non-sense here, please do let me know.