Passing just a type as a parameter in C

Question

Hypothetically it d be handy for me to do this   foo GetColumnValues dm mainColumn  int  foo GetColumnValues dm mainColumn  string    where the GetColumns method will call a different method inside depending on the type passed   Yes  I could do it as a boolean flag or similar  I just wondered if there was a way to perhaps pass this  and then ask   typeof arg 1   or similar     I could also override the method  use generics  etc - I know there are  different ways to do this  I was just curious if this was possible

User · Answer

foo GetColumnValues dm mainColumn  typeof int    foo GetColumnValues dm mainColumn  typeof string      Or using generics   foo GetColumnValues lt int gt  dm mainColumn   foo GetColumnValues lt string gt  dm mainColumn

User · Answer

Use generic types      class DataExtraction lt T gt        DateRangeReport dateRange      List lt Predicate gt  predicates      List lt string gt  cids       public DataExtraction  DateRangeReport dateRange                             List lt Predicate gt  predicates                             List lt string gt  cids                             this dateRange   dateRange          this predicates   predicates          this cids   cids            And call it like this      DataExtraction lt AdPerformanceRow gt  extractor   new DataExtraction lt AdPerformanceRow gt  dates  predicates   cids

User · Answer

You can use an argument of type Type - iow  pass typeof int   You can also use generics for a  probably more efficient  approach

User · Answer

foo GetColumnValues dm mainColumn  typeof string    Alternatively  you could use a generic method   public void GetColumnValues lt T gt  object mainColumn        GetColumnValues mainColumn  typeof T        and you could then use it like   foo GetColumnValues lt string gt  dm mainColumn

User · Answer

You can do this  just wrap it in typeof    foo GetColumnValues typeof int    public void GetColumnValues Type type          logic

User · Answer

There are two common approaches   First  you can pass System Type  object GetColumnValue string columnName  Type type           Here  you can check specific types  as needed       if  type    typeof int              This would be called like  int val    int GetColumnValue columnName  typeof int     The other option would be to use generics   T GetColumnValue lt T gt  string columnName           If you need the type  you can use typeof T       This has the advantage of avoiding the boxing and providing some type safety  and would be called like   int val   GetColumnValue lt int gt  columnName

User · Answer

You can pass a type as an argument  but to do so you must use typeof   foo GetColumnValues dm mainColumn  typeof int     The method would need to accept a parameter with type Type        where the GetColumns method will call a different method inside depending on the type passed    If you want this behaviour then you should not pass the type as an argument but instead use a type parameter   foo GetColumnValues lt int gt  dm mainColumn

[c#] Passing just a type as a parameter in C#

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