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Mruby

mruby page

Some notes on the mruby C API

Common things

MRB_API - This declares functions that are meant to be accessed externally. They seem unlikely to change. They are also exported when built dynamically. Other functions in the headers but not MRB_API seem to be subject to change at any time.

mrb_sym - This datatype basically means Ruby symbol :something. You can easily get this by using the mrb_inter_lit(mrb, "symbol"). This is the equivalent of #to_sym

mrb_value - This is Ruby's boxed type. This type is used nearly everywhere where different types can be accepted. See below for more information about how to box and unbox data.

mruby Data types and C Data types

RBasic

Possibly BasicObject. Not sure. Every other R* type can cast to this, since it only consists of the MRB_OBJECT_HEADER

RObject

The mruby object. The difference between this and RBasic is this one can have instance variables.

RArray

Represents an array. You cannot actually cast this to RObject! Its got no space for instance variables.

RClass

Represents a class.

RCptr

Not sure. C Pointer?? Declared in boxing_word.h.

RData

Extended version of the RObject that can contain custom data.

REnv

Not sure what this is. Declared in proc.h

RException

Exception object. Its exactly the same as an RObject.

RProc

A Ruby proc. Procs in Ruby only represent a list of instructions. You can literally insert these anywhere and they can freely change control flow within the scope because they have no scope themselves. You cannot cast this to RObject. It is made of mrb_irep, a somewhat mysterious object to me right now.

RBreak

Breakpoint? Not sure

RFiber

Don't know what a fiber is. Declared in object.h

RFloat

Not sure why this is a thing. Declared in boxing_word.h.

RHash

A Ruby hash. This is an RObject plus a hashtable.

RRange

RString

Functions (Variables)

MRB_API mrb_value mrb_gv_get(mrb_state *mrb, mrb_sym sym);

Gets a global variable.

  • mrb is the state.
  • sym is the symbol of the global variable. You can actually pass syms that do not start with $. However you cannot access them in ruby, because $ tells the interpreter its a global variable. Could be good for hiding things but could also be subject to change.

MRB_API void mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value val);

Sets a global variable

  • mrb is the state.
  • sym same as mrb_gv_get.
  • val the value to set the variable to.

MRB_API void mrb_gv_remove(mrb_state *mrb, mrb_sym sym);

Removes a global variable. Actually not sure what happens when theres no global.

MRB_API mrb_value mrb_const_get(mrb_state*, mrb_value, mrb_sym);

MRB_API void mrb_const_set(mrb_state*, mrb_value, mrb_sym, mrb_value);

MRB_API mrb_bool mrb_const_defined(mrb_state*, mrb_value, mrb_sym);

MRB_API mrb_bool mrb_const_defined_at(mrb_state *mrb, mrb_value mod, mrb_sym id);

MRB_API void mrb_const_remove(mrb_state*, mrb_value, mrb_sym);

MRB_API mrb_value mrb_iv_get(mrb_state *mrb, mrb_value obj, mrb_sym sym);

MRB_API void mrb_iv_set(mrb_state *mrb, mrb_value obj, mrb_sym sym, mrb_value v);

MRB_API mrb_value mrb_obj_iv_get(mrb_state *mrb, struct RObject *obj, mrb_sym sym);

MRB_API void mrb_obj_iv_set(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v);

MRB_API mrb_bool mrb_iv_name_sym_p(mrb_state *mrb, mrb_sym sym);

MRB_API void mrb_iv_name_sym_check(mrb_state *mrb, mrb_sym sym);

MRB_API mrb_bool mrb_obj_iv_defined(mrb_state *mrb, struct RObject *obj, mrb_sym sym);

MRB_API mrb_bool mrb_iv_defined(mrb_state*, mrb_value, mrb_sym);

MRB_API mrb_value mrb_iv_remove(mrb_state *mrb, mrb_value obj, mrb_sym sym);

MRB_API void mrb_iv_copy(mrb_state *mrb, mrb_value dst, mrb_value src);

MRB_API mrb_value mrb_cv_get(mrb_state *mrb, mrb_value mod, mrb_sym sym);

MRB_API void mrb_cv_set(mrb_state *mrb, mrb_value mod, mrb_sym sym, mrb_value v);

MRB_API void mrb_mod_cv_set(mrb_state *mrb, struct RClass * c, mrb_sym sym, mrb_value v);

MRB_API mrb_bool mrb_cv_defined(mrb_state *mrb, mrb_value mod, mrb_sym sym);

Functions (Boxing)

Simple Types

MRB_INLINE mrb_value mrb_nil_value(void)

MRB_INLINE mrb_value mrb_false_value(void)

MRB_INLINE mrb_value mrb_true_value(void)

MRB_INLINE mrb_value mrb_bool_value(mrb_bool boolean)

MRB_INLINE mrb_value mrb_undef_value(void)

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