Is memory used by an object's declared, but undefined member?

If my class has declared a

private var _iDontGetDefined:EnormousObject;

but never creates anything to be stored 开发者_JAVA技巧there, does this impact performance or use a significant amount of memory?

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Such declaration will not affect performance and will have almost no impact on memory footprint.

If you want to maintain a lot of similar and optional values, you may consider using a Dictionary.