flex-devel

[Flex-devel] api change for [yy]input()

[Nate R. <na...@go...>]

I recently discovered that the behavior of input() has changed from
returning EOF at end of file to returning 0. Searching around I came across
a closed github issue (https://github.com/westes/flex/issues/212), but this
really feels like something for the mailing list. So:

Why change this return value, potentially breaking callers? Is it simply
because Apple chose to do so (
https://opensource.apple.com/source/flex/flex-26/patches/scanEOF.diff.auto.html)?
If that's the case, perhaps the man page should be updated to match.

I did my best to search for discussion around December 2015 on this mailing
list but didn't see any; please feel free to just point me to an existing
thread if this has already been covered.

Best,

--nate

Re: [Flex-devel] api change for [yy]input()

[Will E. <wes...@gm...>]

On Monday, 22 May 2017, 11:10 pm +0000, Nate Rosenblum <na...@go...> wrote:

> I recently discovered that the behavior of input() has changed from
> returning EOF at end of file to returning 0. Searching around I came across
> a closed github issue (https://github.com/westes/flex/issues/212), but this
> really feels like something for the mailing list. So:
> 
> Why change this return value, potentially breaking callers? Is it simply
> because Apple chose to do so (
> https://opensource.apple.com/source/flex/flex-26/patches/scanEOF.diff.auto.html)?
> If that's the case, perhaps the man page should be updated to match.

There was a reason why, but it escapes me. It's on my list and I keep thinking I will get to it and I keep not getting to it. I imagine this involves looking at the code and git blame in various ways.

It was not solely because Apple. There was some particular thing that made me think it was a good idea.

If you can point me to an example in the wild where this is a problem, that helps a bunch.

Failing that, your point about updating the documentation is a good one -- and pull requests against github are easy for me to process.

Re: [Flex-devel] api change for [yy]input()

[Nate R. <na...@go...>]

On Sun, Jun 25, 2017 at 12:34 PM Will Estes <wes...@gm...> wrote:

> On Monday, 22 May 2017, 11:10 pm +0000, Nate Rosenblum <na...@go...>
> wrote:
>
> > I recently discovered that the behavior of input() has changed from
> > returning EOF at end of file to returning 0. Searching around I came
> across
> > a closed github issue (https://github.com/westes/flex/issues/212), but
> this
> > really feels like something for the mailing list. So:
> >
> > Why change this return value, potentially breaking callers? Is it simply
> > because Apple chose to do so (
> >
> https://opensource.apple.com/source/flex/flex-26/patches/scanEOF.diff.auto.html
> )?
> > If that's the case, perhaps the man page should be updated to match.
>
> There was a reason why, but it escapes me. It's on my list and I keep
> thinking I will get to it and I keep not getting to it. I imagine this
> involves looking at the code and git blame in various ways.
>
> It was not solely because Apple. There was some particular thing that made
> me think it was a good idea.
>
> If you can point me to an example in the wild where this is a problem,
> that helps a bunch.
>
> Failing that, your point about updating the documentation is a good one --
> and pull requests against github are easy for me to process.
>

Thanks for getting back to me.

For my use case, the change is not a significant problem (just unexpected);
I already had to special-case the return value on OSX builds.

It seems like this change could, however, make it quite hard to use
yyinput() when scanning syntaxes that allow embedded null characters.
Returning -1 on end of file allows one to differentiate end of file
conditions from valid 0 bytes.

--nate