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Re: [Pharo-users] FFI return by reference

by Esteban Lorenzano

> On 08 Apr 2016, at 11:34, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: > > >> On 07 Apr 2016, at 14:15, Damien Pollet <damien.pollet+pharo(a)gmail.com <mailto:damien.pollet+pharo@gmail.com>> wrote: >> >> I think in that case you need to pass an instance of FFIExternalValueHolder. > > yes. > you can take the test FFIExternalValueHolderTests>>testCall as an example. > > But since it uses anonymous classes it might require a better explanation, there is the class comment, but basically, you do this: > > 1) Declare a class variable > > MyClass class>>initialize > INT_PTR := FFIExternalValueHolder ofType: âintâ. as a larger explanation, this will create an anonymous subclass to keep âintâ values, than later you can use as a type in your function call. Some people would call this obscure, but is a good way of solving this problem (I adopted it from old NB). If you want to have a named class instead an anonymous class, you can just subclass FFIExternalValueHolder: FFIExternalValueHolder subclass: #MyIntPtr and then implement typeDecl class method MyIntPtr class>>typeDecl ^ âint' and this will work as the anonymous class > > 2) Replace "int *â in your function calls with your new type: > > glGetAttribute: attr into: value > ^ self ffiCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, INT_PTR value) ) > > 3) pass an instance of INT_PTR to get the value: > > | ptr value | > > ptr := INT_PTR new. > self glGetAttribute: anAttributeIDontKnow into: ptr. > > value := ptr value. > > Esteban > > >> >> On 7 April 2016 at 17:42, Thibault Raffaillac <thibault.raffaillac(a)inria.fr <mailto:thibault.raffaillac@inria.fr>> wrote: >> Hi again, >> >> Does anyone know what is the state of return by reference in FFI? >> Example: >> glGetAttribute: attr into: value >> <primitive: #primitiveNativeCall module: #NativeBoostPlugin error: errorCode> >> ^ self nbCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, int *value) ) >> >> On my image (50666) it does nothing on value yet (if nil, remains nil, if SmallInteger 0, remains 0). >> (SDL2 glGetAttribute: 6 into: value) should return 16. >> I've seen NBOpenGL put "out" before value in method header, should it matter? (does not make it work though) >> Last but not least, should we attach '*' to the type or variable for FFI to understand it is a pointer? >> >> Cheers, >> Thibault Raffaillac >> >> >

April 8, 2016

Re: [Pharo-users] FFI return by reference

by Esteban Lorenzano

> On 07 Apr 2016, at 14:15, Damien Pollet <damien.pollet+pharo(a)gmail.com> wrote: > > I think in that case you need to pass an instance of FFIExternalValueHolder. yes. you can take the test FFIExternalValueHolderTests>>testCall as an example. But since it uses anonymous classes it might require a better explanation, there is the class comment, but basically, you do this: 1) Declare a class variable MyClass class>>initialize INT_PTR := FFIExternalValueHolder ofType: âintâ. 2) Replace "int *â in your function calls with your new type: glGetAttribute: attr into: value ^ self ffiCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, INT_PTR value) ) 3) pass an instance of INT_PTR to get the value: | ptr value | ptr := INT_PTR new. self glGetAttribute: anAttributeIDontKnow into: ptr. value := ptr value. Esteban > > On 7 April 2016 at 17:42, Thibault Raffaillac <thibault.raffaillac(a)inria.fr <mailto:thibault.raffaillac@inria.fr>> wrote: > Hi again, > > Does anyone know what is the state of return by reference in FFI? > Example: > glGetAttribute: attr into: value > <primitive: #primitiveNativeCall module: #NativeBoostPlugin error: errorCode> > ^ self nbCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, int *value) ) > > On my image (50666) it does nothing on value yet (if nil, remains nil, if SmallInteger 0, remains 0). > (SDL2 glGetAttribute: 6 into: value) should return 16. > I've seen NBOpenGL put "out" before value in method header, should it matter? (does not make it work though) > Last but not least, should we attach '*' to the type or variable for FFI to understand it is a pointer? > > Cheers, > Thibault Raffaillac > >

April 8, 2016

Re: [Pharo-users] Passing nil with FFI

by Esteban Lorenzano

Hi, marshalling in UFFI is complex and sometimes not worthy, so we do not do auto-conversion between nil in smalltalk o zero to NULL (yes, I know NULL=0, but not for UFFI who is waiting a object type). In this case (since it expects a kind of external object) you have to do: SDL2 glCreateContext: FFIExternalObject null. Esteban > On 07 Apr 2016, at 12:06, Thibault Raffaillac <thibault.raffaillac(a)inria.fr> wrote: > > Hi, > > I am having trouble passing nil to a function with FFI (i.e. NULL, i.e. 0). > For example: SDL2 glCreateContext: nil. > The function expects a subclass of FFIExternalObject, so calls instVarAt: 1 but nil has no such field! > Am I missing something? (like a special nil instance of FFIExternalObject) > Note however that putting nil works when FFI expects a String. > > Cheers, > Thibault Raffaillac >

April 8, 2016

Re: [Pharo-users] FFI return by reference

by Thibault Raffaillac

Is there something like a generic int value holder then? > > I think in that case you need to pass an instance of FFIExternalValueHolder. > > > Hi again, > > > > Does anyone know what is the state of return by reference in FFI? > > Example: > > glGetAttribute: attr into: value > > <primitive: #primitiveNativeCall module: #NativeBoostPlugin error: > > errorCode> > > ^ self nbCall: #( int SDL_GL_GetAttribute(SDL_GLattr attr, int > > *value) ) > > > > On my image (50666) it does nothing on value yet (if nil, remains nil, if > > SmallInteger 0, remains 0). > > (SDL2 glGetAttribute: 6 into: value) should return 16. > > I've seen NBOpenGL put "out" before value in method header, should it > > matter? (does not make it work though) > > Last but not least, should we attach '*' to the type or variable for FFI > > to understand it is a pointer? > > > > Cheers, > > Thibault Raffaillac

April 8, 2016

Re: [Pharo-users] Debugger in 4.0

by Hilaire

I open a bug ticket, it is important https://pharo.fogbugz.com/f/cases/17961/Evaluating-instance-and-method-vari… -- Dr. Geo http://drgeo.eu

April 8, 2016

Re: [Pharo-users] Pharo-users Question about the symbols

by Cyril Ferlicot Delbecque

On 08/04/2016 09:05, Henrik Nergaard wrote: > | s1 s2 | > > s1 := 1234 asString. > s2 := 1234 asString. > > s1 = s2. "true" > s1 == s2. "false" > > s1 asSymbol = s2 asSymbol. "true" > s1 asSymbol == s2 asSymbol. "true" > > (s1 class allInstances select: [:s | s = s1 ]) size. "2" > (s1 asSymbol class allInstances select: [:s | s = s1 asSymbol ]) size. "1" > > [ #stringA = #stringB ] bench. "26,812,864 per second" > [ 'StringA' = 'StringB' ] bench. "3,492,987 per second" > > Best regards, > Henrik Hi Henrik, The class comment of Symbol is really not enough. It need improvement. I think it would be good to add your examples at least in the class comment. -- Cyril Ferlicot http://www.synectique.eu 165 Avenue Bretagne Lille 59000 France

April 8, 2016

Re: [Pharo-users] Pharo-users Question about the symbols

by stepharo

+1 >> | s1 s2 | >> >> s1 := 1234 asString. >> s2 := 1234 asString. >> >> s1 = s2. "true" >> s1 == s2. "false" >> >> s1 asSymbol = s2 asSymbol. "true" >> s1 asSymbol == s2 asSymbol. "true" >> >> (s1 class allInstances select: [:s | s = s1 ]) size. "2" >> (s1 asSymbol class allInstances select: [:s | s = s1 asSymbol ]) size. "1" >> >> [ #stringA = #stringB ] bench. "26,812,864 per second" >> [ 'StringA' = 'StringB' ] bench. "3,492,987 per second" > very very nice summary. >

April 8, 2016

Re: [Pharo-users] Pharo-users Question about the symbols

by Sven Van Caekenberghe

> On 08 Apr 2016, at 09:19, Damien Cassou <damien.cassou(a)inria.fr> wrote: > > Henrik Nergaard <henrik.nergaard(a)uia.no> writes: > >> | s1 s2 | >> >> s1 := 1234 asString. >> s2 := 1234 asString. >> >> s1 = s2. "true" >> s1 == s2. "false" >> >> s1 asSymbol = s2 asSymbol. "true" >> s1 asSymbol == s2 asSymbol. "true" >> >> (s1 class allInstances select: [:s | s = s1 ]) size. "2" >> (s1 asSymbol class allInstances select: [:s | s = s1 asSymbol ]) size. "1" >> >> [ #stringA = #stringB ] bench. "26,812,864 per second" >> [ 'StringA' = 'StringB' ] bench. "3,492,987 per second" > > very very nice summary. YES! > -- > Damien Cassou > http://damiencassou.seasidehosting.st > > "Success is the ability to go from one failure to another without > losing enthusiasm." --Winston Churchill

April 8, 2016

Re: [Pharo-users] Pharo-users Question about the symbols

by Damien Cassou

Henrik Nergaard <henrik.nergaard(a)uia.no> writes: > | s1 s2 | > > s1 := 1234 asString. > s2 := 1234 asString. > > s1 = s2. "true" > s1 == s2. "false" > > s1 asSymbol = s2 asSymbol. "true" > s1 asSymbol == s2 asSymbol. "true" > > (s1 class allInstances select: [:s | s = s1 ]) size. "2" > (s1 asSymbol class allInstances select: [:s | s = s1 asSymbol ]) size. "1" > > [ #stringA = #stringB ] bench. "26,812,864 per second" > [ 'StringA' = 'StringB' ] bench. "3,492,987 per second" very very nice summary. -- Damien Cassou http://damiencassou.seasidehosting.st "Success is the ability to go from one failure to another without losing enthusiasm." --Winston Churchill

April 8, 2016

Re: [Pharo-users] Pharo-users Question about the symbols

by Henrik Nergaard

| s1 s2 | s1 := 1234 asString. s2 := 1234 asString. s1 = s2. "true" s1 == s2. "false" s1 asSymbol = s2 asSymbol. "true" s1 asSymbol == s2 asSymbol. "true" (s1 class allInstances select: [:s | s = s1 ]) size. "2" (s1 asSymbol class allInstances select: [:s | s = s1 asSymbol ]) size. "1" [ #stringA = #stringB ] bench. "26,812,864 per second" [ 'StringA' = 'StringB' ] bench. "3,492,987 per second" Best regards, Henrik -----Original Message----- From: Pharo-users [mailto:pharo-users-bounces@lists.pharo.org] On Behalf Of Ben Coman Sent: Friday, April 8, 2016 3:23 AM To: Any question about pharo is welcome <pharo-users(a)lists.pharo.org> Subject: Re: [Pharo-users] Pharo-users Question about the symbols A symbol is like a string, except that all symbols with the same value are in fact the same object; that is, every #hello symbol is the exact same object as every other #hello symbol. See "identically equal" section here... http://sdmeta.gforge.inria.fr/FreeBooks/ByExample/08%20-%20Chapter%206%20-%… cheers, ben On Fri, Apr 8, 2016 at 7:20 AM, Valentin Ryckewaert <valentin.ryckewaert(a)gmail.com> wrote: > Hello everyone, > > i'm learning Pharo and i'm having difficulties to understand the > symbols, what are they? How are they different of the ByteString ? Why > are they usefull ? > Why should I put #string where I can put 'string' ? > > Thanks in advance for your answer. > Valentin Ryckewaert

April 8, 2016