World: r3wp
[Red] Red language group
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Kaj 18-Jun-2011 [2083] | I once did, but I doubt it will now compensate for c-string! and NULL |
Dockimbel 18-Jun-2011 [2084] | Integer! is conceptually the closest type to handle!. |
Kaj 18-Jun-2011 [2085] | Yes, so why not define NULL and byte-ptr! as integer? |
Dockimbel 18-Jun-2011 [2086] | About NULL, please read the ticket on github I have posted above. NULL will be changed. |
Kaj 18-Jun-2011 [2087x2] | Sure, but why not fix this inconvenience right now? |
I don't care what handle! is, just that there are three incompatible definitions | |
Dockimbel 18-Jun-2011 [2089] | Because I currently work on another ticket. |
Kaj 18-Jun-2011 [2090x2] | It's just changing the two lines I cited above |
I don't mean right now right now, I mean before making NULL polymorphic | |
Dockimbel 18-Jun-2011 [2092] | The NULL changes will be done this weekend, you won't have to wait too long. |
Kaj 18-Jun-2011 [2093] | That still leaves the incompatibility between byte-ptr! and the documentation |
Dockimbel 18-Jun-2011 [2094] | byte-ptr! as integer?: certainly not, byte-ptr! as it names implies is a byte! pointer, so semantically different than just integer!. |
Kaj 18-Jun-2011 [2095] | But you're saying all the time that a void pointer is conceptually closest to an integer? |
Dockimbel 18-Jun-2011 [2096x2] | Right. |
You should erase the "void pointer" expression from your mind, it is corrupting your vision. :-) | |
Kaj 18-Jun-2011 [2098x2] | Again, I don't care much what it is (although I wouldn't expect ALLOCATE to return a c-string!), just that the definitions are compatible, so you don't have to insert confusing typecasts everywhere |
I'm just following what you have written in the manual about pointers | |
Dockimbel 18-Jun-2011 [2100] | the definitions are compatible : which ones? |
Kaj 18-Jun-2011 [2101] | NULL, byte-ptr! and the manual use three type incompatible definitions. I must compare and pass these types |
Dockimbel 18-Jun-2011 [2102] | NULL and documentation will be fixed during this weekend. |
Kaj 18-Jun-2011 [2103] | So will they be compatible with byte-ptr! thereafter? |
Dockimbel 18-Jun-2011 [2104x2] | NULL should work with any kind of pointer/struct or be removed. |
I haven't decided yet on the right solution, but you can safely use ALLOCATE as it is defined right now, that won't be changed. | |
Kaj 18-Jun-2011 [2106] | Not really, because casts are needed on every use of ALLOCATE and FREE |
Dockimbel 18-Jun-2011 [2107x2] | That would be the case whatever type you would put in the return definition of ALLOCATE? |
As you can allocate memory space for various datatypes. | |
Kaj 18-Jun-2011 [2109] | No, because there's one exception: the type that ALLOCATE and FREE choose to use |
Dockimbel 18-Jun-2011 [2110] | You've lost me...what type are you talking about? |
Kaj 18-Jun-2011 [2111] | They currently use c-string! I'm not sure that's the clearest one. It's unintuitive to me, as if the type returned is very specific and comes with a zero byte at the end |
Dockimbel 18-Jun-2011 [2112] | That is why I have not put c-string! but byte-ptr!. |
Kaj 18-Jun-2011 [2113] | I know, but that gets lost during compilation. What the compiler complains about is that you have to cast to and from c-string! |
Dockimbel 18-Jun-2011 [2114x2] | Do I really need to add a new [pointer! [byte!]] to the compiler just to make this error message looks nicer? |
(I mean adding a new datatype in the compiler). | |
Kaj 18-Jun-2011 [2116] | I think that would be very useful, but that's the more fundamental pointer discussion. I'm now just concerned about making casts the least confusing |
Dockimbel 18-Jun-2011 [2117x2] | I pretty sure that some ppl would complain that [pointer! [byte!]] is exactly the same as c-string!...;-) |
I don't get what is the issue with casting (expect the error message)? | |
Kaj 18-Jun-2011 [2119] | Sure, but I mean, we had two definitions of a generic pointer: integer! or pointer! [integer!]. Why confuse it with c-string! now? |
Dockimbel 18-Jun-2011 [2120x7] | expect => except |
Well, I have already answered that question above. I am sorry if that change breaks existing code. Once again, the C void pointer is a very confusing concept that should not be used outside of C language. If you refer to a C void pointer without any context, it is just a memory address, so integer! (or handle!) would be the closest corresponding concept. If you refer to a C function returning a void pointer like malloc(), the closest transposition in Red/System would be ALLOCATE returning a byte! pointer. | |
Malloc() allocates a memory region that granularity is by default a byte (until you cast is to something else). | |
So, in summary, there is no 1 to 1 transposition of the C void pointer concept in Red/System, it is 1 to 2 (or more), depending on the context. | |
If you would write a C function such as: void *bar() { return((void *)&foo);) where foo would be another function. If I had to make a binding to this function from Red, I would use integer! (or preferably the handle! macro) to define the return value. | |
Six months ago, I wanted to introduce an address! type to be the equivalent of C void pointer. It would have worked as an integer!. But as it would have been only used to in C binding definitions, I thought it would be a waste to have a first-class datatype just for that, when integer!, pointer! [...], or a macro could do the same job. | |
If [pointer! [byte!]] could do the job and make C coders happy, I will add it to Red/System. | |
Kaj 18-Jun-2011 [2127x5] | I'm not concerned with all that here. Let me make this very concrete. In runtime/common.reds, changing |
#define byte-ptr! c-string! | |
to | |
#define byte-ptr! pointer [integer!] | |
Would solve all my current concerns | |
Dockimbel 18-Jun-2011 [2132] | Well, this is certainly not the right definition a byte! pointer. :-) Can't you wait until monday when all the current issues regarding NULL and documentation will be fixed? |
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