On Wed, 17 Oct 2012 13:34:57 -0300 Gustavo Sverzut Barbieri
<barbi...@profusion.mobi> said:
> On Wed, Oct 17, 2012 at 11:27 AM, Carsten Haitzler
> <ras...@rasterman.com>wrote:
>
> > On Wed, 17 Oct 2012 10:01:23 -0300 Gustavo Sverzut Barbieri
> > <barbi...@profusion.mobi> said:
> >
> > did u read the docs provided? they provide example use cases (simplified).
> >
> > as to the below - the cost of the ptr isn't worth worrying about - they are
> > temporary... VERY temporary. it's a special thing to allow c to be more
> > like
> > js/lua/shell etc. think of eobj. now we do things like
> >
> > obj = eo_add(class, parent,
> > GEOMETRY(10, 20, 50, 30),
> > FILE_SET("/path/to/file"),
> > GROUP_SET("groupname"));
> >
> > ok - so file is a constant string. so is group. now let's pretend we want
> > to
> > FIND a data file in a path or relative to the apps installed dir at
> > runtime and
> > we have:
> >
> > const char *file_find(const chart *file);
> >
> > how could i do something convenient like
> >
> > obj = eo_add(class, parent,
> > GEOMETRY(10, 20, 50, 30),
> > FILE_SET(file_find("image.jpg")),
> > GROUP_SET(group_find("base")));
> >
> > the only way is to provide a buffer to snprintf into OR to return a
> > strduped or
> > strinshare'd string... the problem is all our existing api doesn't free
> > this
> > string afterwards. it has no idea where the string came from so you CANNOT
> > do
> > the above as you will leak strings as no one frees them. the alternative is
> > that you have to do it in 2 stages - get the strings first, then call the
> > api,
> > then free them afterwards. imaging you wanted to find 2 different files -
> > so
> > you couldnt use a static char buffer either as u'd overwrite the same
> > buffer
> > within the call args.
> >
> > tmpstr solves that by provide a very short list of "currently active"
> > strings
> > that are duplicated and survive as a return string SO they can be passed
> > in as
> > params to the method above and then be freed by the method when done. the
> > advantage is they are really simple and trivially detected as being a
> > tmpstr or
> > not. if not it does what it does now - leaves it alone. it may be a const
> > str
> > or some other buffer that doesn't need freeing here. this system is to be
> > able
> > to preserve an entire string as a return value long enough to go INTO
> > another
> > func as is given as examples in the docs.
> >
> > this is also part of making things IDE friendly. as above with FILE_SET
> > literally an IDE could provide not just autocomplete but once u start
> > typeing
> > in FILE_SET(... pop up a file browser to select a data file from your apps
> > "project tree" without having to find the full file name and just put it in
> > there with the file find api as above nicely for you. as you scroll around
> > a
> > thumbnail of the file is provided above.near the entry in the src and if u
> > want
> > ot change it just click on it and select something else. it's making it
> > user
> > friendly AND compact. it's one step of many.
> >
>
> Cedric did explain this to me, and I'm worried and scared the way things
> are going.
>
> In my opinion this will break expectation and will induce users to leak.
how so? it works exactly as it does now, but in addition allows for throwing
tmpstr's around.
> They already leak now, where the expected behavior is "i receive a const, I
> don't keep it, you must free afterwards". If you introduce "I receive a
> const, which I may free", then you'll see leaks to show more and more. This
> is based on USER, not our code.
>
> As usual the problem will be to handle the incorrect usage and corner cases.
>
> I agree C is cumbersome and you always need 3 lines, one to
> declare-type-and-get, another for the real call, another to release. But
> that's the language you choose for the project. So keeping it consistent
> would be nice.
eo is about making it less cumbersome. tmpstr plugs a usability hole that
forces both current api and eo to become more combersome. hell we cann add a
tmpstr_cleanup() that we call on idle enter to plug such leaks - then the
maximum domain for a tmpstr to survive is until entering idle. already cleaned
up strs are gone and ones someone forgot to free will now be gone too.
--
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler) ras...@rasterman.com
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