March 2014 - cffi-devel - mailman3.common-lisp.net

[cffi-devel] cffi-grovel: signal GROVEL-ERROR instead of CL:SIMPLE-ERROR
by Anton Vodonosov 29 Apr '14

29 Apr '14

Hello. In the cl-test-grid project we test how every library in Quicklisp is compiled and also run some test suites. Then we build reports, review regressions and submit bugs to library authors. It is very often that machine where tests are run don't have some foreign library, of don't have a C compiler. For libraries using cffi-grovel it results in cl:simple-error: External process exited with code 1. (example log: http://cl-test-grid.appspot.com/blob?key=1sisosse6j) This kind of errors are not regressions, so we don't want to report them. It would be very helpful to distinguish such errors automatically, because they are not regressions and we don't need to report them to authors. As this type of errors happens all the time during testing on various machines, automation will save us significant efforts. We could easily distinguish these errors if cffi-grovel signaled specific condition instead of generic cl:simple-error. Possible simple fix is to introduce new condition cffi-grovel:grovel-error and shadow cl:error in the cffi-grovel package, instead writing an own cff-givel:error function with the same prototype as cl:error, but with the condition type it signals will be cffi-grovel:grovel-error. If you agree to this proposal I am willing to provide a patch. Best regards, - Anton

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[Cffi-devel] Pre-populate cffi:*foreign-library-directories* by OS
by Liam Healy 07 Apr '14

07 Apr '14

>From time to time I have seen requests from users to include an absolute path (starting from "/") in systems that use load-foreign-library under a clause for their favorite OS. This makes me nervous, especially when it is a little-used OS, because I have the feeling the requester's configuration is not typical for that OS and I will later get a request to add a different path when the original requester has moved on. Ideally, there would never have to be any absolute paths; dlopen would always know where to find libraries, because the OS is always configured in a standard way. However, a quick survey of this topic shows that reality falls far short of this ideal, and remedies are not clear. It is well beyond our capabilities to fix the entire world on this matter. Between fixing the world and fixing every CFFI-using application one by one, there is the compromise of setting default search paths for each OS in CFFI itself, thereby opening all applications to proper functionality out of the box for most OSes. The variable cffi:*foreign-library-directories* seems like the right thing to set. I've looked through all Quicklisp libraries for absolute paths in uses of load-foreign-library, and found these: Solaris: /lib/64, /usr/lib/amd64, /usr/lib Darwin: /usr/lib, /opt/local/lib, /usr/local/lib Unix: /usr/local/lib, /usr/lib Therefore I propose to change the definition to: (defvar *foreign-library-directories* '(#+(or unix darwin solaris) "/usr/lib" #+(or unix darwin) "/usr/local/lib" #+darwin "/opt/local/lib" #+solaris "/lib/64" #+solaris "/usr/lib/amd64") "List onto which user-defined library paths can be pushed.") As requests come in to add an absolute path for an application, they can be referred to this mailing list to request the change here, if it is not an application-specific path. Then it is more likely to be properly vetted for general applicability for all users of that OS, and will be available for all libraries. Does this sound like a reasonable way to handle this problem? Liam

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[cffi-devel] HDF5 bindings
by Jeff Cunningham 03 Apr '14

03 Apr '14

I noticed that Daniel Herring posted a set of bindings to the C HDF5 library back in 2011. I'd like to write some higher level functions to make working with (at least simple) files of this type easier. Has anyone worked with these bindings? I'm not a CFFI expert and would benefit greatly from a sample or two. Kind regards, --Jeff Cunningham

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Re: [Cffi-devel] Fw: Casting variables and functions
by Joeish W 31 Mar '14

31 Mar '14

I was just wondering why cffi doesn't do automatic conversions. Since casting is used so much in c I think it would do automatic conversions...Do experts in CFFI normally use this approach, do they cast on the Lisp side or use another approach..I'd like to start learning the best way to do things On , Joeish W <joeish80829(a)yahoo.com> wrote: On Sunday, March 30, 2014 7:53 AM, Joeish W <joeish80829(a)yahoo.com> wrote: > >I was just wondering why cffi doesn't do automatic conversions. Since casting is used so much in c I think it would do automatic conversions...Do experts in CFFI normally use this approach, do they cast on the Lisp side or use another approach..I'd like to start learning the best way to do things >> >>On Sunday, March 30, 2014 7:45 AM, Stelian Ionescu <sionescu(a)cddr.org> wrote: >> >>On Sun, 2014-03-30 at 07:18 -0700, Joeish W wrote: >>>> Thanks for getting back to me., I really appreciate it >>> >>>> Using coerce though I'm already casting it to a float on the lisp >>>> side...I was wondering if I can cast a 4 to a float with CFFI and have >>>> the output be a 4.0f0 like it works in C...without doing anything on >>>> the Lisp side >>> >>>CFFI doesn't do automatic coercions, but you can do it with a custom >>>type: >>> >>>(define-foreign-type float+int () () >>> (:actual-type :float) >>> (:simple-parser float+int)) >>> >>>(defmethod expand-to-foreign (value (type float+int)) >>> `(coerce ,value 'float)) >>> >>>(with-foreign-object (val :float) >>> (setf (mem-ref val 'float+int) 4) >>> (mem-ref val :float)) >>> >>> >>>-- >>>Stelian Ionescu a.k.a. fe[nl]ix >>>Quidquid latine dictum sit, altum videtur. >>> >>> >>> >> >> > >

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[Cffi-devel] Casting variables and functions
by Joeish W 31 Mar '14

31 Mar '14

This is the way I thought you did it but I'm running this and it's not working: (with-foreign-object (float :float) (setf float 6) (type-of float)) >(INTEGER 0 4611686018427387903) The output says it is an integer I tried this: (with-foreign-object (float :float) (setf (mem-ref float :float) 4) (type-of (mem-ref float :float))) And get this error: Value of #1=#:VALUE4 in (SB-KERNEL:%SET-SAP-REF-SINGLE FLOAT 0 #1#) is 4, not a SINGLE-FLOAT. [Condition of type SIMPLE-TYPE-ERROR] If someone could help me cast in CFFI I would appreciate it. the word "cast" isn't even in the CFFI documentation. I just would like to be able to cast anything, from functions to variable into other types. Any maybe if someone skilled in CFFI can tell me if it so good that it can do any thing you can in C. I would appreciate that too.

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[Cffi-devel] writing documentation for CFFI functions
by Joeish W 30 Mar '14

30 Mar '14

Which is the better way do write documentation for functions for a CFFI library like this? C++: int RNG::uniform(int a, int b) Common Lisp: (UNIFORM-D (RNG (:POINTER RNG)) (A :DOUBLE) (B :DOUBLE)) => :DOUBLE or like this without the parenthesis C++: float RNG::uniform(float a, float b) Common Lisp: (UNIFORM-F (RNG :POINTER RNG) A :FLOAT B :FLOAT) => :FLOAT

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[cffi-devel] New and delete pertaining C wrapper for C++ code
by Joeish W 23 Mar '14

23 Mar '14

I have a whole list of C wrappers for OpenCV C++ functions like the one below. And all of them return a "new". I can't change them because they are becoming part of OpenCV and it would make my library perfect to have a consistently updated skeleton to wrap around. My question is in this case how would one of you free these "new" memory allocators...When I run them in any kind of loop. It just eats up my ram, I end up having to restart my pc. Should I make a "delete" wrapper and use that. I've tried using foreign-free but I still have the same issue of having to restart. Any help is appreciated. Mat* cv_create_Mat() { return new Mat(); }

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[cffi-devel] Creating a pointer to a C string
by Joeish W 19 Mar '14

19 Mar '14

I'm trying to recreate a const char* filename parameter for code I have that needs it...The function I'm wrapping is the OpenCV C++ function "imread" it is below in the documentation. It is used to read an image(jpg etc) from a file and return a pointer to it http://docs.opencv.org/modules/highgui/doc/reading_and_writing_images_and_v… first I need to wrap in C as below calling the const char* filename parameter as a String* the below cv_imread does compile on ubuntu trusty using g++. And the function works as intended using g++. Mat* cv_imread(String* filename, int flags) { return new Mat(cv::imread(*filename, flags)); } I wrap in Lisp like this: (defcfun ("cv_imread" %imread) (:pointer mat) (filename (:pointer string*)) (flags :int)) When I usually create a (:pointer string*) parameter I do it like this (window-name (foreign-alloc :string :initial-element "IMREAD Example")) and it works to supply strings that aren't filenames but when I try to use a filename both absolute and relative paths it fails...it also fails using double forward slashes in the pathname. Any advice is appreciated and btw Emacs /SBCL is my Lisp IDE

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[cffi-devel] How would I wite the return value for a defcfun in my documentation
by Joeish W 11 Mar '14

11 Mar '14

Here is my defcfun as I normally write it, ;; Size Mat::size() const ;; Size* cv_Mat_size(Mat* self) (defcfun ("cv_Mat_size" mat-size) (:pointer size) (self (:pointer mat))) the ;; Size Mat::size() const is the C++ function declaration with a Size return value The ;; Size* cv_Mat_size(Mat* self) is the C wrapper function declaration with a Size* return value This is my defcfun with a (:pointer size) return value (defcfun ("cv_Mat_size" mat-size) (:pointer size) (self (:pointer mat))) In my Documentation for this function I list the Common Lisp function declaration as (MAT-SIZE (SELF (:POINTER MAT))) I couldn't figure out if I should add a return value but in C++ the return value always goes up front i/e ;; Size Mat::size() const Is it common to put return values on Lisp/CFFI function declarations and if so where in this declaration (MAT-SIZE (SELF (:POINTER MAT))) should I put mine btw on the CLHS I didn't see or missed return values on any function declaration Thanks in advance for any takers=) Good Day.

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[cffi-devel] CFFI 0.12.0 released
by Luís Oliveira 05 Mar '14

05 Mar '14

Hello everyone, I've just released CFFI 0.12.0. See <https://github.com/cffi/cffi/wiki/NEWS> for a summary of what's new since the previous release. Cheers, -- Luís Oliveira http://kerno.org/~luis/

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