2016-01-10 16:57 GMT+01:00 Eliot Miranda <eliot.miranda at gmail.com>:

>
> Hi Nicolai,
>
> On Sun, Jan 10, 2016 at 3:16 AM, Nicolai Hess <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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