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Re: Const structure pointer as template argument

Subject: Re: Const structure pointer as template argument
From: Ladd Van Tol <email@hidden>
Date: Fri, 30 Jun 2006 09:05:16 -0700
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On Jun 30, 2006, at 1:55 AM, Paul Walmsley wrote:

Unless you're trying to do something very subtle, I reckon that this is really what you wanted to do:

   struct testStruct
   {
       long a;
   };

   template <class T> class Helper
   {
   };

   testStruct nonConstTestStruct = {0};
   Helper<testStruct*> HelperNonConst;

   const testStruct constTestStruct = {0};
   Helper<const testStruct*> HelperConst;


Nope, the code in question needs the actual instance.

If you had a need to pass a const or non-const pointer into the Helper so that it references a testStruct, then change the definition to this:
   template <class T> class Helper
   {
       Helper(T object) : myObject(object) {};
       T   myObject;
   };
   const testStruct constTestStruct = {0};
   Helper<const testStruct*> HelperConst(&constTestStruct);

Yes, this is how I would have written it, but it's a large legacy source base, and changing it is not an option.

Also, the construct I described appears to compile in CodeWarrior and Visual Studio. Not always the best indicator of standards compliance, but there you have it.

- Ladd

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References:
	>Const structure pointer as template argument (From: Ladd Van Tol <email@hidden>)
	>Re: Const structure pointer as template argument (From: Paul Walmsley <email@hidden>)

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