Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 24 Jun 2013 12:16:10 -0500

Hi Michael,

On 2013-06-24 Michael Abbott wrote:
> On Mon, 24 Jun 2013, Andrew Johnson wrote:
> > This is a C API, C doesn't have closures
> 
> Of course C has closures, they just require a little cooperation from the
> called function part.  A closure in C is a function taking at least one
> void* parameter together with a void* value to pass to it.

The void* parameter is what we've always regarded as a context pointer for 
the function.  The storage for that data has to be managed by the programmer 
though, so while it performs the same job as a closure it isn't a real one.

http://en.wikipedia.org/wiki/Closure_(computer_science) says:
  "The idiom is similar to closures in functionality, but not in syntax."

> In truth a C++ closure is exactly the same thing, only in disguise.

C++11 has closures which it calls lambda-expressions; they look very useful, 
but do move the language even more in the direction of line-noise IMHO.

- Andrew
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System