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From: Catonano
Subject: dynamic-wind
Date: Fri, 30 Jun 2017 22:33:02 +0200

On the irc channel I was suggested that it might have been a good fit for
my use case

I took a look at it in the manual

I'm perplexed. I don't understand it

How is it supposed to be used ?

The provided example is somewhat contrived, I couldn't understand it anyway.

My use case is basic, really.

I have a scheme wrap around a C library for reading xls files, freexl.

Freexl uses a pointer to a structure tha represents the opened xls file and
its contents

Each function writes/reads in the memory region pointed to such pointer.

In the end, it requires to use a function that closes the file AND frees
all the involved structures in memory.

So my idea was that I would have gotten a simple macro, like this

(with-xls-file "path/to/my/xls-file.xls" handler-ptr
   (do-something handler-ptr)
   (do-something-more handler-ptr))

and this would have expanded to

(freexl-open "path/to/my/xls-file.xls" handler-ptr)
(freexl-do-something handler-ptr)
(freexl-do-something-more handler-ptr))
(freexl-close handler-ptr)

Do I need dynamic-wind at all ?

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