The same applies if you define a procedure with a set of overloads and declare a static variable with the same name in each overload. The initialization of one of these variables does not affect the values of the others. If you do this, the Visual Basic compiler considers each such variable to be a separate element. You can declare static variables with the same name in more than one procedure. When the instance is released for garbage collection (GC) The first time the procedure is called on the specific instance In an instance of a class, not Shared (procedure is an instance member) The first time the procedure is called either on a specific instance or on the class or structure name itself In a class, Shared (procedure is not an instance member) The following table shows how the procedure declaration determines how long a Static variable exists. If you declare a local variable with the Static keyword, its lifetime is longer than the execution time of its procedure. However, Shared variables are preserved until your application stops running.
Each new instance of the class or structure creates and reinitializes its nonshared variables. When an instance of a class or structure terminates, its nonshared variables lose their memory and their values. The next time you call the procedure, all its local variables are created afresh and reinitialized. When a procedure terminates, the values of its local variables are not preserved, and Visual Basic reclaims their memory.
RUN FUNCTION AS SOON AS ELEMENT EXISTS CODE
These initializations take effect whether or not your code ever executes the block. Variables declared within a block inside a procedure (such as a For loop) are initialized on entry to the procedure.
Similarly, each element of an array variable is initialized individually. When the procedure encounters a Dim statement that specifies initial values, it sets those variables to those values, even if your code had already assigned other values to them.Įach member of a structure variable is initialized as if it were a separate variable. Every local variable is initialized to the default value for its data type as soon as the procedure begins running. Beginning of LifetimeĪ local variable's lifetime begins when control enters the procedure in which it is declared. However, if that procedure calls other procedures, the local variables retain their values while the called procedures are running. This applies also to that procedure's parameters and to any function return. However, a Shared variable has only a single lifetime, which lasts for the entire time your application is running.Ī local variable (declared inside a procedure) exists only while the procedure in which it is declared is running. Each such variable has the same lifetime as its instance. A nonshared variable declared in a class or structure exists as a separate copy for each instance of the class or structure in which it is declared. Different LifetimesĪ member variable (declared at module level, outside any procedure) typically has the same lifetime as the element in which it is declared. Its value can change over its lifetime, but it always holds some value. The lifetime of a variable represents the period of time during which it can hold a value. For this purpose, the compiler treats procedure parameters and function returns as special cases of variables. Variables are the only elements that have lifetime. The lifetime of a declared element is the period of time during which it is available for use.
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