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Re: Eliminating nested functions

From: Bean
Subject: Re: Eliminating nested functions
Date: Sat, 18 Apr 2009 03:33:56 +0800


One of the advantage of nested function is to use local variables.
Without it, we would need to pass them as global variable, or add
custom data pointer in many of the iterate function, which would make
the code a lot uglier IMO.

On Fri, Apr 17, 2009 at 11:54 PM, Pavel Roskin <address@hidden> wrote:
> Hello!
> While I have just applied a patch adding NESTED_FUNC_ATTR to several
> functions as an emergency fix for a major breakage in ata, ohci, uhci
> and lspci modules, I would prefer a more radical solution.
> I suggest that we eliminate all nested functions.  The reasons are:
> 1) They make the code less readable, as they make the parent functions
> longer.
> 2) They have problems with some popular compilers, as recent as gcc-4.0
> when regparm(3) is used.
> 3) We failed to implement a reliable test for such problems.  We are
> using regparm(1) for all compilers.
> 4) The existing test is one of the obstacles making it impossible to
> compile without having libc for the target (x86_64->i386 would be really
> nice), as we need to run the compiled test executable.
> 5) Non-i386 architectures define NESTED_FUNC_ATTR as an empty symbol, so
> developers on such architectures don't see if they use it correctly.
> 6) NESTED_FUNC_ATTR tends to proliferate to the file scope functions, as
> it happened with grub_pci_iterate().  It only takes one caller using a
> nested function to force NESTED_FUNC_ATTR on all functions used as an
> argument to the same function.
> We can give all formerly nested functions better, more descriptive names
> starting like other functions in the file and ending with "_iter".
> --
> Regards,
> Pavel Roskin
> _______________________________________________
> Grub-devel mailing list
> address@hidden


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