diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/extension.rdoc | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/doc/extension.rdoc b/doc/extension.rdoc index a4996920f9..50320502f1 100644 --- a/doc/extension.rdoc +++ b/doc/extension.rdoc @@ -657,14 +657,11 @@ with the next macro. TypedData_Wrap_Struct() returns a created Ruby object as a VALUE. -The klass argument is the class for the object. +The klass argument is the class for the object. It is recommended +that klass derives from rb_cObject. data_type is a pointer to a const rb_data_type_t which describes how Ruby should manage the struct. -It is recommended that klass derives from a special class called -Data (rb_cData) but not from Object or other ordinal classes. -If it doesn't, you have to call rb_undef_alloc_func(klass). - rb_data_type_t is defined like this. Let's take a look at each member of the struct. @@ -819,6 +816,8 @@ Here's the example of an initializing function. { /* define DBM class */ VALUE cDBM = rb_define_class("DBM", rb_cObject); + /* Redefine DBM.allocate + rb_define_alloc_func(rb_cDBM, fdbm_alloc); /* DBM includes Enumerable module */ rb_include_module(cDBM, rb_mEnumerable); @@ -828,7 +827,7 @@ Here's the example of an initializing function. /* DBM instance method close(): no args */ rb_define_method(cDBM, "close", fdbm_close, 0); /* DBM instance method []: 1 argument */ - rb_define_method(cDBM, "[]", fdbm_fetch, 1); + rb_define_method(cDBM, "[]", fdbm_aref, 1); /* ... */ @@ -851,10 +850,19 @@ TypedData_Make_Struct. RUBY_TYPED_FREE_IMMEDIATELY, }; - obj = TypedData_Make_Struct(klass, struct dbmdata, &dbm_type, dbmp); + static VALUE + fdbm_alloc(VALUE klass) + { + struct dbmdata *dbmp; + /* Allocate T_DATA object and C struct and fill struct with zero bytes */ + return TypedData_Make_Struct(klass, struct dbmdata, &dbm_type, dbmp); + } This code wraps the dbmdata structure into a Ruby object. We avoid wrapping DBM* directly, because we want to cache size information. +Since Object.allocate allocates an ordinary T_OBJECT type (instead +of T_DATA), it's important to either use rb_define_alloc_func() to +overwrite it or rb_undef_alloc_func() to delete it. To retrieve the dbmdata structure from a Ruby object, we define the following macro: @@ -872,9 +880,13 @@ There are three kinds of way to receive method arguments. First, methods with a fixed number of arguments receive arguments like this: static VALUE - fdbm_delete(VALUE obj, VALUE keystr) + fdbm_aref(VALUE obj, VALUE keystr) { - /* ... */ + struct dbmdata *dbmp; + GetDBM(obj, dbmp); + /* Use dbmp to access the key */ + dbm_fetch(dbmp->di_dbm, StringValueCStr(keystr)); + /* ... */ } The first argument of the C function is the self, the rest are the |