Dan Sugalski:
# At 1:14 PM -0700 5/15/02, Brent Dax wrote:
# >Dan Sugalski:
# ># At 12:51 AM -0700 5/15/02, Brent Dax wrote:
# ># >-Parrot becomes Parrot_Interp
# ># >-Parrot_String is gone and the string_funcs.h functions are # no
# >longer # >externally visible. -A few structures have been renamed.
# ># >-config.h has been rearranged so that INTVAL, etc. are now
# ># aliases for
# ># >Parrot_Int, etc.
# ># >-A few things that were accidentally made external no longer are.
# >#
# ># This isn't a problem with config.h. config.h should *never* be used
# ># by anyone embedding Parrot, either directly or indirectly.
# >
# >Why not? Some parts of Parrot's embedding system have to be
# set up by
# >Configure.
#
# And those parts should go in embed.h. The bare minimum amount of
# stuff should go in there--the definitions of INTVAL, NUMVAL, Buffer,
# STRING (maybe), and the exported functions. A later phase of the
# build could probably set this up as well, as it'd have access to more
# information.
I'm trying to keep the number of dynamically-generated files to a
minimum. We don't lose anything by defining a small part of config.h
that's external, and we gain a static embed.h.
# Stuff like PMC definitions shouldn't go in it. PMC * should be
# typedef'd to void * in the embedding header.
What I do is declare things like
struct parrot_pmc_t;
typedef struct parrot_pmc_t* Parrot_PMC;
So we don't get warnings about type mismatches when we compile embed.c.
Actually, Parrot_PMC won't be in embed.h directly--it'll be in extern.h,
which defines the interface between the outside world and PMCs and
STRINGs. (I'm planning for extenders to use the same interface, which
is why it's in a separate header. embed.h will probably include
extern.h, so it'll be transparent to the user.)
# ># >I first noticed the problems with computed-goto when I
# found the #
# >>following line in test_main.c: # >
# ># > #ifdef HAVE_COMPUTED_GOTO
# ># >
# ># >See the problem?
# >#
# ># Yes. test_main.c should never have to know about computed
# goto cores
# ># or whatnot. The define's likely something generally passed on the
# ># command line to all the parrot core bits,
# >
# >True. Still, the idea of a define like this not being fixed
# somewhere
# >scares me a bit. If someone tries to send us a copy of
# their config.h
# >so we can debug a problem, we can't tell if they have cgoto enabled.
#
# That's definitely a problem. That #define should be in config.h, and
# *is* a problem.
Actually, the JIT does the same thing, so it's not *entirely* his fault.
# >Actually, it should know that Parrot may support a
# computed-goto core
# >and the flag to enable it is X. It shouldn't have to know if this
# >particular copy of Parrot is built with that capability.
# (It probably
# >should be able to detect it, however, so that it can handle
# cases like
# >the one in test_main's -h handler.)
#
# Flag handling, or at least feature enabling, should probably be done
# by core code. We should provide a set_feature() function
Right now we have something like this:
Parrot_setflag(interpreter, PARROT_CGOTO_FLAG, NULL);
I'm not sure how Parrot reacts to that if computed goto isn't available
on this platform, though.
# ># test_main.c should only use "parrot/embed.h", which
# shouldn't include
# ># any Parrot .h files
# >
# >I'm including three:
# >
# >-parrot/interpreter.h, which provides a forward definition of struct
# >Parrot_Interp and a full definition of enum Parrot_Interp_flag.
#
# We should have a typedef for Parrot_Interp to void * for embedders.
Right now we have a forward declaration of struct Parrot_Interp and a
typedef. The actual body of struct Parrot_Interp is private.
struct Parrot_Interp;
typedef struct Parrot_Interp * Parrot_Interp;
...
#ifdef PARROT_IN_CORE
...
typedef struct Parrot_Interp {
...
} Interp;
...
#endif
# >-parrot/warnings.h, which provides warning classes.
#
# Hrm, good point.
#
# >-parrot/config.h, which provides data like what a Parrot_Int
# (INTVAL)
# >is and what version of Parrot this is.
# >
# >All three are specifically crafted to expose as little as possible.
# >(Well, maybe not config.h, but it doesn't expose anything that isn't
# >prefixed. I should probably move most of the JIT stuff out of the
# >interface. In fact, I'll do that right now.)
#
# Cool.
--Brent Dax <[EMAIL PROTECTED]>
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