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3292 :: templates with generics question

• jackmott (orginal) [2017-10-30T00:20:24+01:00] view original

  The following code works fine as a proc, but not as a template:

  proc BufferData*[T](target:BufferTarget, data:openarray[T], usage:BufferDataUsage)  =
      glBufferData(target.GLenum,data.len*T.sizeof().GLsizeiptr,data.unsafeAddr,usage.GLenum)
  
  Run

  Any obvious reason changing proc to template might go wrong there? It compiles fine, but doesn't run properly.

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• jangko (orginal) [2017-10-31T02:56:04+01:00] view original

  you can always inspect the generated C code to see what are the differences between them.

  One thing I spotted which could be a potential hidden bug is data.unsafeAddr. When the data is an ordinary array, it would be ok. But when it is a seq, crash is almost guaranteed.

  safer way to write it would be data[0].unsafeAddr, safe for array and seq

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• jackmott (orginal) [2017-10-31T14:15:28+01:00] view original

  Thank you, that was indeed the problem, and it makes sense why. As a template it is just being treated as a seq, rather than converted to an openarray as a proc, I suppose.

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