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#ifndef RBIMPL_VARIABLE_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_VARIABLE_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Declares rb_define_variable().
*/
#include "ruby/internal/dllexport.h"
#include "ruby/internal/value.h"
#include "ruby/internal/attr/nonnull.h"
#include "ruby/internal/attr/noreturn.h"
RBIMPL_SYMBOL_EXPORT_BEGIN()
/**
* Type that represents a global variable getter function.
*
* @param[in] id The variable name.
* @param[in,out] data Where the value is stored.
* @return The value that shall be visible from Ruby.
*/
typedef VALUE rb_gvar_getter_t(ID id, VALUE *data);
/**
* Type that represents a global variable setter function.
*
* @param[in] val The value to set.
* @param[in] id The variable name.
* @param[in,out] data Where the value is to be stored.
*/
typedef void rb_gvar_setter_t(VALUE val, ID id, VALUE *data);
/**
* Type that represents a global variable marker function.
*
* @param[in] var Where the value is to be stored.
*/
typedef void rb_gvar_marker_t(VALUE *var);
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_getter_t rb_gvar_undef_getter;
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_setter_t rb_gvar_undef_setter;
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_marker_t rb_gvar_undef_marker;
/**
* This is the getter function that backs global variables defined from a ruby
* script. Extension libraries can use this if its global variable needs no
* custom logic.
*/
rb_gvar_getter_t rb_gvar_val_getter;
/**
* This is the setter function that backs global variables defined from a ruby
* script. Extension libraries can use this if its global variable needs no
* custom logic.
*/
rb_gvar_setter_t rb_gvar_val_setter;
/**
* This is the setter function that backs global variables defined from a ruby
* script. Extension libraries can use this if its global variable needs no
* custom logic.
*/
rb_gvar_marker_t rb_gvar_val_marker;
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_getter_t rb_gvar_var_getter;
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_setter_t rb_gvar_var_setter;
/**
* @deprecated
*
* This function has no actual usage (than in ruby itself). Please ignore. It
* was a bad idea to expose this function to 3rd parties, but we can no longer
* delete it.
*/
rb_gvar_marker_t rb_gvar_var_marker;
RBIMPL_ATTR_NORETURN()
/**
* This function just raises ::rb_eNameError. Handy when you want to prohibit
* a global variable from being squashed by someone.
*/
rb_gvar_setter_t rb_gvar_readonly_setter;
RBIMPL_ATTR_NONNULL(())
/**
* "Shares" a global variable between Ruby and C. Normally a Ruby-level global
* variable is stored somewhere deep inside of the interpreter's execution
* context, but this way you can explicitly specify its storage.
*
* ```CXX
* static VALUE foo;
*
* extern "C" void
* init_Foo(void)
* {
* foo = rb_eval_string("...");
* rb_define_variable("$foo", &foo);
* }
* ```
*
* In the above example a Ruby global variable named `$foo` is stored in a C
* global variable named `foo`.
*
* @param[in] name Variable (Ruby side).
* @param[in] var Variable (C side).
* @post Ruby level global variable named `name` is defined if absent,
* and its storage is set to `var`.
*/
void rb_define_variable(const char *name, VALUE *var);
RBIMPL_ATTR_NONNULL((1))
/**
* Defines a global variable that is purely function-backended. By using this
* API a programmer can define a global variable that dynamically changes from
* time to time.
*
* @param[in] name Variable name, in C's string.
* @param[in] getter A getter function.
* @param[in] setter A setter function.
* @post Ruby level global variable named `name` is defined if absent.
*
* @internal
*
* @shyouhei doesn't know if this is an Easter egg or an official feature, but
* you can pass 0 to the third argument (setter). That effectively nullifies
* any efforts to write to the defining global variable.
*/
void rb_define_virtual_variable(const char *name, rb_gvar_getter_t *getter, rb_gvar_setter_t *setter);
RBIMPL_ATTR_NONNULL((1))
/**
* Identical to rb_define_virtual_variable(), but can also specify a storage.
* A programmer can use the storage for e.g. memoisation, storing intermediate
* computation result, etc.
*
* Also you can pass 0 to this function, unlike other variants:
*
* - When getter is 0 ::rb_gvar_var_getter is used instead.
* - When setter is 0 ::rb_gvar_var_setter is used instead.
* - When data is 0, you must specify a non-zero setter function. Otherwise
* ::rb_gvar_var_setter tries to write to `*NULL`, and just causes SEGV.
*
* @param[in] name Variable name, in C's string.
* @param[in] var Variable storage.
* @param[in] getter A getter function.
* @param[in] setter A setter function.
* @post Ruby level global variable named `name` is defined if absent.
*/
void rb_define_hooked_variable(const char *name, VALUE *var, rb_gvar_getter_t *getter, rb_gvar_setter_t *setter);
RBIMPL_ATTR_NONNULL(())
/**
* Identical to rb_define_variable(), except it does not allow Ruby programs to
* assign values to such global variable. C codes can still set values at
* will. This could be handy for you when implementing an `errno`-like
* experience, where a method updates a read-only global variable as a side-
* effect.
*
* @param[in] name Variable (Ruby side).
* @param[in] var Variable (C side).
* @post Ruby level global variable named `name` is defined if absent,
* and its storage is set to `var`.
*/
void rb_define_readonly_variable(const char *name, const VALUE *var);
RBIMPL_ATTR_NONNULL(())
/**
* Defines a Ruby level constant under a namespace.
*
* @param[out] klass Namespace for the constant to reside.
* @param[in] name Name of the constant.
* @param[in] val Value of the constant.
* @exception rb_eTypeError `klass` is not a kind of ::rb_cModule.
* @exception rb_eFrozenError `klass` is frozen.
* @post Ruby level constant `klass::name` is defined to be `val`.
* @note This API does not stop you from defining a constant that is
* unable to reach from ruby (like for instance passing
* non-capital letter to `name`).
* @note This API does not stop you from overwriting a constant that
* already exist.
*
* @internal
*
* Above description is in fact inaccurate. This API interfaces with Ractors.
*/
void rb_define_const(VALUE klass, const char *name, VALUE val);
RBIMPL_ATTR_NONNULL(())
/**
* Identical to rb_define_const(), except it defines that of "global",
* i.e. toplevel constant.
*
* @param[in] name Name of the constant.
* @param[in] val Value of the constant.
* @exception rb_eFrozenError ::rb_cObject is frozen.
* @post Ruby level constant \::name is defined to be `val`.
* @note This API does not stop you from defining a constant that is
* unable to reach from ruby (like for instance passing
* non-capital letter to `name`).
* @note This API does not stop you from overwriting a constant that
* already exist.
*/
void rb_define_global_const(const char *name, VALUE val);
RBIMPL_ATTR_NONNULL(())
/**
* Asserts that the given constant is deprecated. Attempt to refer such
* constant will produce a warning.
*
* @param[in] mod Namespace of the target constant.
* @param[in] name Name of the constant.
* @exception rb_eNameError No such constant.
* @exception rb_eFrozenError `mod` is frozen.
* @post `name` under `mod` is deprecated.
*/
void rb_deprecate_constant(VALUE mod, const char *name);
RBIMPL_ATTR_NONNULL(())
/**
* Assigns to a global variable.
*
* @param[in] name Target global variable.
* @param[in] val Value to assign.
* @return Passed value.
* @post Ruby level global variable named `name` is defined if absent,
* whose value is set to `val`.
*
* @internal
*
* Above description is in fact inaccurate. This API interfaces with
* `set_trace_func`.
*/
VALUE rb_gv_set(const char *name, VALUE val);
RBIMPL_ATTR_NONNULL(())
/**
* Obtains a global variable.
*
* @param[in] name Global variable to query.
* @retval RUBY_Qnil The global variable does not exist.
* @retval otherwise The value assigned to the global variable.
*
* @internal
*
* Unlike rb_gv_set(), there is no way to trace this function.
*/
VALUE rb_gv_get(const char *name);
RBIMPL_ATTR_NONNULL(())
/**
* Obtains an instance variable.
*
* @param[in] obj Target object.
* @param[in] name Target instance variable to query.
* @exception rb_eEncodingError `name` is corrupt (contains Hanzi etc.).
* @retval RUBY_nil No such instance variable.
* @retval otherwise The value assigned to the instance variable.
*/
VALUE rb_iv_get(VALUE obj, const char *name);
RBIMPL_ATTR_NONNULL(())
/**
* Assigns to an instance variable.
*
* @param[out] obj Target object.
* @param[in] name Target instance variable.
* @param[in] val Value to assign.
* @exception rb_eFrozenError Can't modify `obj`.
* @exception rb_eArgError `obj` has too many instance variables.
* @return Passed value.
* @post An instance variable named `name` is defined if absent on
* `obj`, whose value is set to `val`.
*
* @internal
*
* This function does not stop you form creating an ASCII-incompatible instance
* variable, but there is no way to get one because rb_iv_get raises exceptions
* for such things. This design seems broken... But no idea why.
*/
VALUE rb_iv_set(VALUE obj, const char *name, VALUE val);
RBIMPL_SYMBOL_EXPORT_END()
#endif /* RBIMPL_VARIABLE_H */
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