DDK Config and Data Attributes

[sbeadle1]

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and attributes are applied to variables in the same way as ConfigField() and DataField().

The member variable Must be declared public ie

 Public mVar as Int32.

Failure to do this will mean the variable is not stored in the specified stream.

Config/Data Properties

The following code will NOT work

 Private _Blue as String  _  _ Public Property Blue() As String  Get   Return _Blue  End Get  Set(ByVal value As String)   _Blue = value  End Set End Property

The following code does...

  Public _Blue as String  _  _ Public Property Blue() As String  Get   Return _Blue  End Get  Set(ByVal value As String)   _Blue = value  End Set End Property

Issues

This means the standard programming pattern of accessing private variables via a property and optionally making the property read-only cannot be implemented.

In the code above, Blue and Blue are both accessible to the DDK code directly.

Scope

Attribute	Properties	OPC View	SQL	DDK
Data()	No	No	No	Yes
DataField()	No	Yes a	Yes a	No b
Config()	No	No	No	Yes
ConfigField()	Yes	Yes	Yes	No b
No Attrib	No	No	No	Yes c

^a DataFields can be made to be read only using ReadOnly:=True
^b DDK accesses ConfigField() and DataField() member variables directly not via the field name.
^c Variables without attributes are not synchronised or saved.

Dynamic()

The atribute can be used to synchronise a public variable. However it is not saved to disk.




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