well… UnifiedFFI, UFFI or whatever it will be called already does that… as you know.
Currently we are using “older” NB way: as a method call, then solving it in first call. This is nice because is compatible and easies some stuff. 
But final objective is to provide a pragma and solve it in compilation time. 

Then we can 100% deprecate the invalid pragma old FFI uses today. 

At least, that’s what we have talk :)

Esteban

> On 12 Jan 2016, at 20:06, Nicolai Hess <nicolaihess at gmail.com> wrote:
> 
> 
> 
> 2016-01-10 16:57 GMT+01:00 Eliot Miranda <eliot.miranda at gmail.com <mailto:eliot.miranda at gmail.com>>:
>  
> Hi Nicolai,
> 
> On Sun, Jan 10, 2016 at 3:16 AM, Nicolai Hess <nicolaihess at gmail.com <mailto:nicolaihess at gmail.com>> wrote:
> pharo fogbugz issue: 17359 MessageNotUnderstood: receiver of "keywords" is nil
> 
> 
> is this valid pragma syntax:
> 
>     <apicall: bool 'SetCursorPos' (long long) module: 'user32.dll'>
> 
> As others have said this is not a valid pragma.  A valid pragma is a message expression (a message with no receiver) that has only literal arguments.  There is one exception, to accept a variable name for the error code in a primitive invocation.
> 
> And as Levente has said it is a goal of the new FFI to get rid of the old syntax you show above.
> 
> 
> Thanks Eliot.
> 
> I think I will wait what Esteban will say to this, he put those classes in the image, maybe he had a plan for the new ffi/apicall syntax
> 
> 
> 
> And as Igor Stasenko discovered /any/ C signature can be written as a literal Array, providing we allow underscores in Symbols (which is a preference).  So for example, the heapsort declaration from the standard C library:
> 
> int
>      heapsort(void *base, size_t nel, size_t width,
>          int (*compar)(const void *, const void *)) 
> 
> could be written as a pragma via e.g.
> 
>     <ffiCCall: #(int heapsort(void *base, size_t nel, size_t width, int (*compar)(const void *, const void *)))>
> 
> in which case it is equal to
> 
>    <ffiCCall: #(#int #heapsort #( #void #* #base #, #size_t #nel #, #size_t #width #, #int #( #* #compar ) #( #const #void #*, #const #void #*)))>
> 
> which, while a massive hack, is pretty neat.  The only difficulty in parsing the above s that void *, is #void #*, not #void #* #,.
> 
> So for me, the natural pragma syntax for the new FFI should be a single keyword starting with ffi that includes the language with which to parse the pragma's argument, followed by a literal Array containing the signature (rather than e.g. a String).  I'd also provide a special-purpose pretty-printer for literal arrays that would be used to pretty-print the above, e.g. when decompiling.
> 
> This would easily allow extensions such as
> 
>      <ffiCcall: #(wchar_t * wcschr(const wchar_t *s, wchar_t c)) arg1is: #UnicodeString arg2is: Character>
> 
> to guide a marshalling engine in providing automatic checks and conversions.
> 
> [Slightly OT]
> Note that I'm already using this syntax in Alien callbacks because one thing it does is to normalize the signature, eliminating the significance of most whitespace (the #*, above being one example where it fails).  So a Callback for heapsort above looks like
> 
> voidstarvoidstarRetint: callbackContext sp: spAlien
> 	<signature: #(int (*)(const void *, const void *)) abi: #IA32>
> 	^callbackContext wordResult:
> 		(block
> 			value: (Alien forPointer: (spAlien unsignedLongAt: 1))
> 			value: (Alien forPointer: (spAlien unsignedLongAt: 5)))
> 
> or
> voidstarvoidstarRetintARM32: callbackContext sp: spAlien
> 	<signature: #(int (*)(const void *, const void *)) abi: #ARM32>
> 	^callbackContext wordResult:
> 		(block
> 			value: (Alien forPointer: (spAlien registerAt: 1))
> 			value: (Alien forPointer: (spAlien registerAt: 2)))
> 
> 
> Hmmm, if Callback had subclasses for each ABI then the above would become
> 
> IA32Callback methods for signature
> voidstarvoidstarRetint: callbackContext sp: spAlien
> 	<signature: #(int (*)(const void *, const void *))>
> 	^callbackContext wordResult:
> 		(block
> 			value: (Alien forPointer: (spAlien unsignedLongAt: 1))
> 			value: (Alien forPointer: (spAlien unsignedLongAt: 5)))
> 
> ARM32Callback methods for signatures
> voidstarvoidstarRetint: callbackContext sp: spAlien
> 	<signature: #(int (*)(const void *, const void *))>
> 	^callbackContext wordResult:
> 		(block
> 			value: (Alien forPointer: (spAlien registerAt: 1))
> 			value: (Alien forPointer: (spAlien registerAt: 2)))
> 
> Much nicer.  I shall make it so.
> 
> our (pharo) parser can not parse this (does not recognizes the
> "selector parts" (apicall:module:) right)
> 
> Any recommendations how to fix this
> - fix RBParser or
> - change this pragma, for example, like this
>   <apicall: #(bool SetCursorPos (long long)) module: 'user32.dll'>
> 
> 
> nicolai
> 
> _,,,^..^,,,_
> best, Eliot
> 
> 

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