Re: [SMARTY-DEV] Re: [SMARTY] Re:[SMARTY-DEV]$smarty.session.object doesn't work in 2.5.0

The value is not referenced if: 1) the value being assigned is an array 2) the value being assigned is an object Otherwise you are correct, only a reference counter is incremented. Monte On Tue, 2003-04-15 at 14:22, Wom.bat wrote: > > Right, but Smarty's method of variable assignement always makes a copy > > regardless of the data type. > As far as I can see that, Smarty does > > $this->_tpl_vars[$tpl_var] = $value; > > This creates _definitely_ a reference to $value, as long as $value is not > altered. Actually, it is not possible to force the copying of a variable. > Always creating references as long as the assigned variables are not altered > is a feature which has been introduced with PHP4 in order to avoid > unnecessary overhead. > Read http://www.zend.com/zend/art/ref-count.php, especially on > from > paragraph "What is variable counting". > > You may also look this up in the PHP source, 4.3.1, zend_execute.c, function > zend_assign_to_variable, lines 413-487 (explanation follows below): > > if (PZVAL_IS_REF(variable_ptr)) { > if (variable_ptr!=value) { > short refcount=variable_ptr->refcount; > zval garbage; > if (type!=IS_TMP_VAR) { > value->refcount++; > } > garbage = *variable_ptr; > *variable_ptr = *value; > variable_ptr->refcount = refcount; > variable_ptr->is_ref = 1; > if (type!=IS_TMP_VAR) { > zendi_zval_copy_ctor(*variable_ptr); > value->refcount--; > } > zendi_zval_dtor(garbage); > } > } else { > variable_ptr->refcount--; > if (variable_ptr->refcount==0) { > switch (type) { > case IS_VAR: > /* break missing intentionally */ > case IS_CONST: > if (variable_ptr==value) { > variable_ptr->refcount++; > } else if (PZVAL_IS_REF(value)) { > zval tmp; > tmp = *value; > zval_copy_ctor(&tmp); > tmp.refcount=1; > zendi_zval_dtor(*variable_ptr); > *variable_ptr = tmp; > } else { > value->refcount++; > zendi_zval_dtor(*variable_ptr); > safe_free_zval_ptr(variable_ptr); > *variable_ptr_ptr = value; > } > break; > case IS_TMP_VAR: > zendi_zval_dtor(*variable_ptr); > value->refcount=1; > *variable_ptr = *value; > break; > EMPTY_SWITCH_DEFAULT_CASE() > } > } else { /* we need to split */ > switch (type) { > case IS_VAR: > /* break missing intentionally */ > case IS_CONST: > if (PZVAL_IS_REF(value) && value->refcount > 0) { > ALLOC_ZVAL(variable_ptr); > *variable_ptr_ptr = variable_ptr; > *variable_ptr = *value; > zval_copy_ctor(variable_ptr); > variable_ptr->refcount=1; > break; > } > *variable_ptr_ptr = value; > value->refcount++; > break; > case IS_TMP_VAR: > ALLOC_ZVAL(*variable_ptr_ptr); > value->refcount=1; > **variable_ptr_ptr = *value; > break; > EMPTY_SWITCH_DEFAULT_CASE() > } > } > (*variable_ptr_ptr)->is_ref=0; > } > > The first if: > if the left variable (represented by the pointer variable_ptr) is a > reference, the value is assigned to the reference. > Otherwise (here we go, the variable is NOT a reference): > First, the refcount is decreased, because the variable gets a new value. > If then the refcount is zero, the allocated memory for variable_ptr is > reused. > If the refcount is not zero, we cannot do this, as we would overwrite all > other variables > (remember: internally, the variable is still stored as a refernce to the > value it has been assigned before) > In this case, it is checked if the value (that shall be assigned to the > variable) itself is a reference. > If this is the case, it gets copied to the memory space of the variable > pointer. > (NOTE: a TMP_VAR is a literal (i.e. a number, string, NULL or boolean > written DIRECTLY into the code, like $foo = 5;), > a CONST is a variable, i.e. sth like $foo = $bar;) > After that, the memory adress of our variable gets changed to the memory > adress of the value assigned, and the reference counter is increased :) > So we have evidence: definitely a reference, even if not explicitely > assigned as one :) > > Well, now I am curious what you're gonna say about that ;) > > Regards, > David -- Monte Ohrt <monte@ispi.net>