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Update and extend doc on alignment issues.

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This commit is contained in:
Gael Guennebaud
2016-12-11 22:45:32 +01:00
parent 76fca22134
commit 57acb05eef
3 changed files with 18 additions and 9 deletions
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8
doc/PassingByValue.dox
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@@ -4,21 +4,21 @@ namespace Eigen {
Passing objects by value is almost always a very bad idea in C++, as this means useless copies, and one should pass them by reference instead.
With Eigen, this is even more important: passing \ref TopicFixedSizeVectorizable "fixed-size vectorizable Eigen objects" by value is not only inefficient, it can be illegal or make your program crash! And the reason is that these Eigen objects have alignment modifiers that aren't respected when they are passed by value.
With %Eigen, this is even more important: passing \ref TopicFixedSizeVectorizable "fixed-size vectorizable Eigen objects" by value is not only inefficient, it can be illegal or make your program crash! And the reason is that these %Eigen objects have alignment modifiers that aren't respected when they are passed by value.
So for example, a function like this, where v is passed by value:
For example, a function like this, where \c v is passed by value:
\code
void my_function(Eigen::Vector2d v);
\endcode
needs to be rewritten as follows, passing v by reference:
needs to be rewritten as follows, passing \c v by const reference:
\code
void my_function(const Eigen::Vector2d& v);
\endcode
Likewise if you have a class having a Eigen object as member:
Likewise if you have a class having an %Eigen object as member:
\code
struct Foo