In and Out Parameters and Migrated Style Parameters

Let's examine the "in" and "out" nature of the different parameters

public void Run()
{
    Number myValue = 5;
    NumberColumn myColumn = new NumberColumn();
    myColumn.Value = 7;
    MethodA(myValue);
    MethodA(myColumn);

-   //MethodB(myValue); //this line would not work, since you can't send a value to a parameter of type column
    MethodB(myColumn);

    MethodC(myValue);
    MethodC(myColumn);
}
void MethodA(Number value)
{
    Debug.WriteLine(value);
    value++;
}
void MethodB(NumberColumn column)
{
    Debug.WriteLine(column);
    column.Value++;
}
void MethodC(NumberParameter parameter)
{
    Debug.WriteLine(parameter);
    parameter.Value++;
}

Let's review the execution of this code:

In line 3 we set the value of myValue to 5.
In Line 5 we set the value of myColumn to 7.
In line 6 we call MethodA and send it the value 5 (from the field myValue)
- In line 15, the parameter called value now has the value 5
- In Line 17 we write the value received as a parameter (5) to the "output" window
- In Line 18 we change the value of the parameter called value to 6.
- Since value is of type Number (a "Value" type) that change is local to this method - and will not affect the actual value in the field myValue when MethodA is done executing.
In line 6, once the MethodA is completed, the value in the myValue field stays the same as before the call - 5
In line 7, we call MethodA and send it myColumn. Since myColumn is a column, and MethodA receives a Number (a "Value" type), the code implicitly sends myColumn.Value, which means send the value stored in myColumn (7)
- In Line 15, the parameter called value now has the value 7
- In Line 17 we write the value received as a parameter (7) to the "output" window
- In Line 18 we change the value of the parameter called value to 8.
- Since value is of type Number (a "Value" type) that change is local to this method - and will not affect the actual value in the column myColumn when MethodA is done executing.
Line 9 is skipped, because we can't send a "Value" type to MethodB which accepts only "Column" types
In line 10, we send the column in the field myColumn (that has the value 7) to MethodB
- In line 20 the parameter called column references to the same Column as the one in the field myColumn. This means that any change to the Value of column will be affect the Value of myColumn since both are actually the same Column.
- In Line 22 we write the value received as a parameter (7) to the "output" window
- In Line 23 we change the Value of the column referenced by the parameter column to 8.
- Since column is a Column type (NumberColumn) when we change it's Value we change the value of the column that was sent.
In line 10, once MethodB completed, the value in the column myColumn is now 8, as the column itself was sent to MethodB

Migrated style parameters, `NumberParameter`

In line 12 we are sending the "Value" in myValue(5) to MethodC that accepts a NumberParameter
- In line 25, the parameter parameter now has the value 5 as was sent to it in line 12.
- In Line 27 we write the value received as a parameter (5) to the "output" window
- In Line 28 we change the value of the parameter called parameter to 6.
- Since on line 12, we send a "Value" to MethodC any change made in MethodC is limited to it's scope and will not affect the value once we exit MethodC
In line 12, once MethodC is complete - the value of myValue remains 5.
In line 13, we are sending the "Column" in myColumn (value 8) to MethodC
- In line 25 the parameter called parameter references to the same Column as the one in the field myColumn. This means that any change to the Value of parameter will be affect the Value of myColumn since both are actually referencing to the same Column.
- In Line 27 we write the value received as a parameter (8) to the "output" window
- In Line 28 we change the Value of the parameter referenced by the parameter parameter to 9.
- Since parameter is a NumberParameter and on line 13, we sent it a "Column", when we change it's Value we change the value of the column that was sent.
In line 13, after MethodC is complete, the value of the column referenced in myColumn field is now 9

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In and Out Parameters and Migrated Style Parameters

Migrated style parameters, NumberParameter

Migrated style parameters, `NumberParameter`