Why Use Global And Local Variables?
Imagine a large canvas app with many screens that only uses global variables. When updating a variable’s value the developer must be aware of its impact across all screens. If the developer does not correctly determine how to use a variable there are unintended consequences (i.e. a software bug).
Local variables can only be used on one screen. Developers have an easier time assessing the impact to a single screen as opposed to many screens. Higher quality code can be written at a faster pace.
One-time variables are not persistently stored in memory. After the With function is executed the variable is cleared from memory and cannot be accessed outside of the function.
Variable Scope:-
A variable’s scope determines where it can be referenced in the app. If the variable is required on multiple screens use a global variable. Otherwise, use a local or context variable instead. Choose the proper variable type by determining its scope.
| Variable Type | Declaration Method | Scope |
| Global | Set Function | Variable is available across all app screens |
| Local | UpdateContext Function | Variable is only available on a single app screen |
| One-time | With Function | Variable is only available inside the WITH function |
Usage Examples
Global Variable (SET function)
Set(
gblSalesTaxAmount,
Value(txt_OrderForm_SubtotalAmount.Text) * 0.13
);
Local Variable (UPDATECONTEXT function)
UpdateContext(
{
locLineItemsCount: 0,
locShowConfirmationMenu: false,
locOrderFormMode=Blank()
}
);
One-Time Variable (WITH function)
With(
{varBusinessContact: LookUp(‘Sales Orders’, ID=ThisItem.ID)},
Concatenate(varBusinessContact.FirstName,varBusinessContact.LastName);
