[Insight-developers] memcpy usage in itk and vtk

[Bradley Lowekamp]

Kent,

I am giving some comment to you patch now.

I agree with what you said.

If the thing you are copying is a template, typedef then std::copy should be used.

But there are many cases you change which use static_cast<char*>, in these cases you loose the type safety of std::copy, and I don't see the point of the change.

Brad

On Apr 10, 2013, at 10:09 AM, "Williams, Norman K" <norman-k-williams at uiowa.edu> wrote:

> The big issue I ran into with memcpy was where it happened in a case where
> it was copying an array of objects whose type was a template parameter,
> that could potentially be a C++ class type.
> 
> In that case it is potentially disastrous, and probably hard to debug.
> std::copy & std::fill have requirements with respect to the type of
> objects copied: they need to have an operator= (defined or default) or a
> constructor taking the fill type respectively.
> 
> In our templated code, throwing a compiler error by enforcing those
> constraints is a good thing; where memcpy could silently fail,
> std::copy/std::fill will complain.
> 
> --
> Kent Williams norman-k-williams at uiowa.edu
> 
> 
> 
> 
> 
> 
> On 4/10/13 9:04 AM, "Bradley Lowekamp" <blowekamp at mail.nih.gov> wrote:
> 
>> Bill,
>> 
>> I think that copy is required for generic programming like much of ITK.
>> 
>> But when you have a known type, I don't see any reason to look down on
>> memcpy.
>> 
>> Brad
>> 
>> On Apr 9, 2013, at 5:02 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>> 
>>> Kent says:
>>> "There are (before this patch) 88 calls to memcpy
>>> in the ITK source code."
>>> 
>>> In VTK, there are 2076 uses of memcpy in 452 classes.. Perhaps the
>>> older sibling can learn from the younger.
>>> 
>>> There are 34 uses of std::copy in vtk.
>>> 
>>> Bill
>>> 
>>> --
>>> Unpaid intern in BillsBasement at noware dot com
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> 
> 
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