On Sun, Jan 8, 2012 at 9:25 PM, Stéphane Ducasse
<[email protected]>wrote:
> can you give an example that I understand
> "One thing I strongly recommend is to favor #moduleName over pragmas
> listing the library - imagine changing 2000+ GSL calls if the library name
> changes =:0 "
>
>
Bill: that already exists in FFI.
Stef: what Bill says is that if you bind to a specific library you have to
put its library name in each method that calls a ffi function. Example of
DBX:
apiErrorType: handle number: err
"int odbx_error_type( odbx_t*, int )"
<cdecl: long 'odbx_error_type' (ulong long) module: 'opendbx'>
^ self externalCallFailed
----
apiInitialize: handle backend: backend host: host port: port
"long odbx_init(odbx_t**, char*, char*, char*)"
<cdecl: long 'odbx_init' (ulong* char* char* char*) module: 'opendbx'>
^self externalCallFailed
---
xxx
---
Notice the "module: 'opendbx"
So...if now the library is renamed or whatever, you have to change all
methods. But I don't think this is a real big deal. There are much worst
things.
Finaly, I copy paste an answer from Andreas from a previous thread:
*The Right Way to do this is to have a subclass of ExternalLibrary and
implement the class-side method #moduleName along the lines of:
MyLibrary class>>moduleName
"Answer the module name to use for this library"
Smalltalk platformName = 'Win32' ifTrue:[^'MyLibrary32.dll'].
Smalltalk platformName = 'unix' ifTrue:[
"check various locations and versions"
#('/usr/lib/libMyLibrary.so'
'/usr/lib/libMyLibrary.so.1'
'/usr/lib/libMyLibrary.so.2'
'/usr/share/libMyLibrary.so.1'
'/usr/share/libMyLibrary.so.2'*
*) do:[:location|
(FileDirectory fileExists: location) ifTrue:[^location].
].
^self error:'MyLibrary is not installed'
].
*
*
*
> Tx
>
> On Jan 8, 2012, at 9:18 PM, Schwab,Wilhelm K wrote:
>
> > Stef,
> >
> > Absent the NB experience, +1 to the comments below. FFI has pretty much
> "just worked" for me. We need double arrays. Callbacks would be great.
> One thing I strongly recommend is to favor #moduleName over pragmas
> listing the library - imagine changing 2000+ GSL calls if the library name
> changes =:0 It makes a LOT more sense to have a class per library, and
> that class knows the name to use. That's all the more true when one
> considers code such as ODBC that can run on multiple platforms with
> different names. #moduleName can test the OS and answer the correct name.
> >
> > Bill
> >
> >
> > ________________________________________
> > From: [email protected] [
> [email protected]] on behalf of Stéphane
> Ducasse [[email protected]]
> > Sent: Sunday, January 08, 2012 2:16 PM
> > To: [email protected]
> > Subject: Re: [Pharo-project] Best way for FFI in Pharo
> >
> > thanks for the feedback.
> > We will come back you soon :)
> > Because we should get FFI and NativeBoost fully working :).
> >
> > Stef
> >
> > On Jan 8, 2012, at 7:29 PM, ncalexan wrote:
> >
> >>
> >> fstephany wrote
> >>>
> >>> I'm also a bit lost between all the different options (plugins,
> >>> NativeBoost, FFI, Alien).
> >>>
> >>
> >> I also found this confusing, so let me tell my recent experience and my
> >> conclusion.
> >>
> >> I have written bindings to the SDL game programming library for use with
> >> Pharo. SDL is cross-platform, and I want to support Mac (most of all),
> >> Windows (one must), and Linux (if I must). As far as I can tell, Alien
> is
> >> not cross-platform and not maintained, so I have not spent time
> >> investigating it.
> >>
> >> Following Igor Stasenko's OpenGLSpecs package, I wrote an SDLSpecs
> package
> >> which parses the relevant C header files and then writes either an NB
> or FFI
> >> callout class tree. I need to define a few structures, make a class
> pool
> >> with some constants, and then define lots of callouts, many of which
> take
> >> references to structures (like 'foo(struct x*)').
> >>
> >> I was able to make both work, more or less, on my Macbook Pro, using
> stock
> >> Pharo 1.3 images and Igor's NBCog.app.
> >>
> >> I found NB to be a nicer programmer experience but I found that the FFI
> just
> >> works. There are a lot of gratuitous differences, but:
> >>
> >> * NB requires a VM compiled with a separate plugin (that I built from
> source
> >> with no trouble -- Igor has done splendid work with CMakeVMMaker).
> >> * NB should be faster than the FFI at pretty much everything, but I
> can't
> >> say since I haven't measured.
> >> * NB has useful primitives for determining if your external objects are
> >> still valid and for determining the current operating system (I intend
> to
> >> use these even if I don't use NB).
> >> * NB has very few tests and examples and essentially no documentation.
> >> * NB has a simple conceptual model, but it is still not as simple as
> the FFI
> >> model.
> >> * NB uses variableByteClasses to great advantage -- this is very cool.
> >>
> >> * NB makes it easy to crash your image, since you are evaluating native
> code
> >> in image.
> >> * NB is still, to my eye, raw and untested on Mac. I had problems with
> >> stack alignments in bizarre places, and NB's interaction with garbage
> >> collection basically ended my attempts to use it.
> >> * NB is basically impossible to debug if you aren't very strong with x86
> >> assembly (I'm not even strong with x86 assembly), and the stack
> >> manipulations rendered GDB pretty much useless for me.
> >> * NB does not integrate well with the Pharo tools -- I think the
> >> MethodTrailers are screwing up references, implementors, and source
> views,
> >> but I haven't investigated.
> >> * NB does not seem to support indirections very easily -- I struggled to
> >> understand how to interface to foreign C functions with specs like
> >> 'foo(struct x)', 'foo(struct x *)' and 'foo(struct x **)', and
> eventually
> >> gave up.
> >>
> >> I wanted to help Igor with the NB project, but the NB-OpenGL Mac
> bindings
> >> crash horribly for me, and although I was able to fix them, it I just
> don't
> >> hack enough x86 assembly to figure out all the tricks Igor is doing.
> The
> >> thought of making it all work on 3 platforms, and fix all the tool
> >> integration, was just too much for me.
> >>
> >> In conclusion, I prefer the FFI. It is old, cross platform, well
> tested,
> >> somewhat documented, and reliable. I think Igor has done some amazing
> work
> >> and I do not want to bash his project (and certainly not his code -- the
> >> man's a magician) but the fancy features are not necessary for my
> project.
> >>
> >>
> >> fstephany wrote
> >>>
> >>> Will this interface handle callbacks ?
> >>>
> >>
> >> I do not need callbacks so cannot speak to this issue.
> >>
> >> Yours,
> >> Nick Alexander
> >>
> >> --
> >> View this message in context:
> http://forum.world.st/Best-way-for-FFI-in-Pharo-tp4275467p4276356.html
> >> Sent from the Pharo Smalltalk mailing list archive at Nabble.com.
> >>
> >
> >
> >
>
>
>
--
Mariano
http://marianopeck.wordpress.com
