Re: How to handle nested structs when converting C headers?
On Thu, 12 Dec 2013 00:04:07 -, H. S. Teoh hst...@quickfur.ath.cx
wrote:
On Thu, Dec 12, 2013 at 12:54:58AM +0100, Gary Willoughby wrote:
On Wednesday, 11 December 2013 at 23:38:13 UTC, Adam D. Ruppe wrote:
On Wednesday, 11 December 2013 at 23:35:04 UTC, Gary Willoughby
wrote:
static union internalRep
try
static union InternalRep { /* note the capital letter */
/* snip */
}
InternalRep internalRep;; // still need a decl
Right. But why use the static keyword here?
Because nested structs by default carry a pointer to the containing
struct (or scope), which means it adds extra baggage and you can't
create the nested without also having an instance of the containing
struct.
I would stop nesting the struct definition. I think that is both cleaner
and closer to the original intent - the only reason it is nested in C is
because C allows definition and declaration that way, and D does not.
Then you don't need static at all.
R
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Re: How to handle nested structs when converting C headers?
Regan Heath: I would stop nesting the struct definition. I think that is both cleaner and closer to the original intent - the only reason it is nested in C is because C allows definition and declaration that way, and D does not. Then you don't need static at all. It's mostly a matter of style, but here I prefer a little more the nested form. It's syntactically closer to the original C file, for a D programmer static struct has a known and clear meaning, and putting the structs inside the other keeps the global namespace clean of those inner names. Like with nested functions putting names inside other scoped helps the programmer see they are just needed there. Bye, bearophile
Re: How to handle nested structs when converting C headers?
On 2013-12-11 23:45, Gary Willoughby wrote: How to handle nested structs when converting C headers? In the following snippet i'm currently converting, how would you convert the nested typed union and structures? Would you declare them separately then use their types in the Tcl_Obj struct? or is there a nice way in D to nest them like C? Convert using DStep[1] and see what happens :) [1] https://github.com/jacob-carlborg/dstep -- /Jacob Carlborg
How to handle nested structs when converting C headers?
How to handle nested structs when converting C headers?
In the following snippet i'm currently converting, how would you
convert the nested typed union and structures? Would you declare
them separately then use their types in the Tcl_Obj struct? or is
there a nice way in D to nest them like C?
typedef struct Tcl_Obj {
int refCount; /* When 0 the object will be freed. */
char *bytes;/* This points to the first byte of the
* object's string representation. The array
* must be followed by a null byte (i.e., at
* offset length) but may also contain
* embedded null characters. The array's
* storage is allocated by ckalloc. NULL means
* the string rep is invalid and must be
* regenerated from the internal rep. Clients
* should use Tcl_GetStringFromObj or
* Tcl_GetString to get a pointer to the byte
* array as a readonly value. */
int length; /* The number of bytes at *bytes, not
* including the terminating null. */
Tcl_ObjType *typePtr; /* Denotes the object's type. Always
* corresponds to the type of the object's
* internal rep. NULL indicates the object has
* no internal rep (has no type). */
union { /* The internal representation: */
long longValue; /* - an long integer value. */
double doubleValue; /* - a double-precision floating value. */
VOID *otherValuePtr;/* - another, type-specific value. */
Tcl_WideInt wideValue; /* - a long long value. */
struct {/* - internal rep as two pointers. */
VOID *ptr1;
VOID *ptr2;
} twoPtrValue;
struct {/* - internal rep as a wide int, tightly
* packed fields. */
VOID *ptr; /* Pointer to digits. */
unsigned long value;/* Alloc, used, and signum packed into a
* single word. */
} ptrAndLongRep;
} internalRep;
} Tcl_Obj;
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 22:45:35 UTC, Gary Willoughby wrote: How to handle nested structs when converting C headers? Nested structs and unions like in your example are supported in D too, same syntax, same effect.
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 22:54:04 UTC, Adam D. Ruppe
wrote:
Nested structs and unions like in your example are supported in
D too, same syntax, same effect.
Actually, no, not quite the same syntax, I didn't notice the name
at the end of the C one (in D, the anonymous nested structs and
unions are supported).
But almost the same then: make them a nested type with a name
after the struct or union keyword then the member. So
struct TwoPtrValue {/* - internal rep as
two pointers. */
VOID *ptr1;
VOID *ptr2;
}
TwoPtrValue twoPtrValue;
that's how I'd do it
Re: How to handle nested structs when converting C headers?
Adam D. Ruppe: Nested structs and unions like in your example are supported in D too, same syntax, same effect. But don't forget to add to use static struct instad of struct. Bye, bearophile
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 23:12:39 UTC, bearophile wrote: Adam D. Ruppe: Nested structs and unions like in your example are supported in D too, same syntax, same effect. But don't forget to add to use static struct instad of struct. Bye, bearophile Have you got an example because i always get: tcl.d(713): Error: no identifier for declarator twoPtrValue tcl.d(718): Error: no identifier for declarator ptrAndLongRep tcl.d(719): Error: no identifier for declarator internalRep
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 23:27:57 UTC, Gary Willoughby
wrote:
On Wednesday, 11 December 2013 at 23:12:39 UTC, bearophile
wrote:
Adam D. Ruppe:
Nested structs and unions like in your example are supported
in D too, same syntax, same effect.
But don't forget to add to use static struct instad of
struct.
Bye,
bearophile
Have you got an example because i always get:
tcl.d(713): Error: no identifier for declarator twoPtrValue
tcl.d(718): Error: no identifier for declarator ptrAndLongRep
tcl.d(719): Error: no identifier for declarator internalRep
Like this perhaps:
struct Tcl_Obj
{
int refCount;
char* bytes;
int length;
Tcl_ObjType* typePtr;
static union internalRep
{
c_long longValue;
double doubleValue;
void* otherValuePtr;
Tcl_WideInt wideValue;
static struct twoPtrValue
{
void* ptr1;
void* ptr2;
}
static struct ptrAndLongRep
{
void* ptr;
c_ulong value;
}
}
}
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 23:35:04 UTC, Gary Willoughby
wrote:
static union internalRep
try
static union InternalRep { /* note the capital letter */
/* snip */
}
InternalRep internalRep;; // still need a decl
Re: How to handle nested structs when converting C headers?
Gary Willoughby: Have you got an example because i always get: tcl.d(713): Error: no identifier for declarator twoPtrValue tcl.d(718): Error: no identifier for declarator ptrAndLongRep tcl.d(719): Error: no identifier for declarator internalRep In D you can't define a struct/union and use it to define an instance on the fly. You have to split definition and use in two parts. Bye, bearophile
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 23:36:11 UTC, bearophile wrote:
In D you can't define a struct/union and use it to define an
instance on the fly.
Well, you can if it is anonymous.
struct Foo {
union {
struct { ubyte a; ubyte b; }
ubyte[2] arr;
}
}
That works in D, and it makes foo.a == arr[0] and foo.b == arr[1];
Re: How to handle nested structs when converting C headers?
Adam D. Ruppe:
Well, you can if it is anonymous.
struct Foo {
union {
struct { ubyte a; ubyte b; }
ubyte[2] arr;
}
}
That works in D, and it makes foo.a == arr[0] and foo.b ==
arr[1];
Right :-) I like D structs.
Bye,
bearophile
Re: How to handle nested structs when converting C headers?
On Wednesday, 11 December 2013 at 23:38:13 UTC, Adam D. Ruppe
wrote:
On Wednesday, 11 December 2013 at 23:35:04 UTC, Gary Willoughby
wrote:
static union internalRep
try
static union InternalRep { /* note the capital letter */
/* snip */
}
InternalRep internalRep;; // still need a decl
Right. But why use the static keyword here?
Re: How to handle nested structs when converting C headers?
On Thu, Dec 12, 2013 at 12:54:58AM +0100, Gary Willoughby wrote:
On Wednesday, 11 December 2013 at 23:38:13 UTC, Adam D. Ruppe wrote:
On Wednesday, 11 December 2013 at 23:35:04 UTC, Gary Willoughby
wrote:
static union internalRep
try
static union InternalRep { /* note the capital letter */
/* snip */
}
InternalRep internalRep;; // still need a decl
Right. But why use the static keyword here?
Because nested structs by default carry a pointer to the containing
struct (or scope), which means it adds extra baggage and you can't
create the nested without also having an instance of the containing
struct.
T
--
It is of the new things that men tire --- of fashions and proposals and
improvements and change. It is the old things that startle and
intoxicate. It is the old things that are young. -- G.K. Chesterton
