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diff --git a/sources/shiboken2/ApiExtractor/doc/typesystem_arguments.rst b/sources/shiboken2/ApiExtractor/doc/typesystem_arguments.rst new file mode 100644 index 000000000..16e0678d3 --- /dev/null +++ b/sources/shiboken2/ApiExtractor/doc/typesystem_arguments.rst @@ -0,0 +1,192 @@ +.. _modifying-arguments: + +Modifying Arguments +------------------- + +.. _conversion-rule: + +conversion-rule +^^^^^^^^^^^^^^^ + + The conversion-rule node allows you to write customized code to convert + the given argument between the target language and C++, and it is a child of the modify-argument node. + + .. code-block:: xml + + <modify-argument ...> + <conversion-rule class="target | native"> + // the code + </conversion-rule> + </modify-argument> + + This node is typically used in combination with the replace-type and + remove-argument nodes. The given code is used instead of the generator's + conversion code. + + Writing %N in the code (where N is a number), will insert the name of the + nth argument. Alternatively, %in and %out which will be replaced with the + name of the conversion's input and output variable, respectively. Note the + output variable must be declared explicitly, for example: + + .. code-block:: xml + + <conversion-rule class="native"> + bool %out = (bool) %in; + </conversion-rule> + + .. note:: You can also use the conversion-rule node to specify :ref:`a conversion code which will be used instead of the generator's conversion code everywhere for a given type <conversion-rule-on-types>`. + +remove-argument +^^^^^^^^^^^^^^^ + + The remove-argument node removes the given argument from the function's + signature, and it is a child of the modify-argument node. + + .. code-block:: xml + + <modify-argument> + <remove-argument /> + </modify-argument> + +rename to +^^^^^^^^^ + + The 'rename to' node is used to rename a argument and use this new name in the generated code. + + .. code-block:: xml + + <modify-argument> + <rename to='...' /> + </modify-argument> + + +remove-default-expression +^^^^^^^^^^^^^^^^^^^^^^^^^ + + The remove-default-expression node disables the use of the default expression + for the given argument, and it is a child of the modify-argument node. + + .. code-block:: xml + + <modify-argument...> + <remove-default-expression /> + </modify-argument> + +replace-default-expression +^^^^^^^^^^^^^^^^^^^^^^^^^^ + + The replace-default-expression node replaces the specified argument with the + expression specified by the ``with`` attribute, and it is a child of the + modify-argument node. + + .. code-block:: xml + + <modify-argument> + <replace-default-expression with="..." /> + </modify-argument> + + +replace-type +^^^^^^^^^^^^ + + The replace-type node replaces the type of the given argument to the one + specified by the ``modified-type`` attribute, and it is a child of the + modify-argument node. + + .. code-block:: xml + + <modify-argument> + <replace-type modified-type="..." /> + </modify-argument> + + If the new type is a class, the ``modified-type`` attribute must be set to + the fully qualified name (including name of the package as well as the class + name). + +define-ownership +^^^^^^^^^^^^^^^^ + + The define-ownership tag indicates that the function changes the ownership + rules of the argument object. The ``class`` attribute specifies the class of + function where to inject the ownership altering code. The ``owner`` attribute + specifies the new ownership of the object. It accepts the following values: + + * target: the target language will assume full ownership of the object. + The native resources will be deleted when the target language + object is finalized. + * c++: The native code assumes full ownership of the object. The target + language object will not be garbage collected. + * default: The object will get default ownership, depending on how it + was created. + + .. code-block:: xml + + <modify-argument> + <define-ownership class="target | native" + owner="target | c++ | default" /> + </modify-argument> + + +reference-count +^^^^^^^^^^^^^^^ + + The reference-count tag dictates how an argument should be handled by the + target language reference counting system (if there is any), it also indicates + the kind of relationship the class owning the function being modified has with + the argument. For instance, in a model/view relation a view receiving a model + as argument for a **setModel** method should increment the model's reference + counting, since the model should be kept alive as much as the view lives. + Remember that out hypothetical view could not become parent of the model, + since the said model could be used by other views as well. + The ``action`` attribute specifies what should be done to the argument + reference counting when the modified method is called. It accepts the + following values: + + * add: increments the argument reference counter. + * add-all: increments the reference counter for each item in a collection. + * remove: decrements the argument reference counter. + * set: will assign the argument to the variable containing the reference. + * ignore: does nothing with the argument reference counter + (sounds worthless, but could be used in situations + where the reference counter increase is mandatory + by default). + + .. code-block:: xml + + <modify-argument> + <reference-count action="add|add-all|remove|set|ignore" variable-name="..." /> + </modify-argument> + + + The variable-name attribute specifies the name used for the variable that + holds the reference(s). + + +replace-value +^^^^^^^^^^^^^ + + The ``replace-value`` attribute lets you replace the return statement of a + function with a fixed string. This attribute can only be used for the + argument at ``index`` 0, which is always the function's return value. + + .. code-block:: xml + + <modify-argument index="0" replace-value="this"/> + + +parent +^^^^^^ + + The parent node lets you define the argument parent which will + take ownership of argument and will destroy the C++ child object when the + parent is destroyed. + + .. code-block:: xml + + <modify-argument index="1"> + <parent index="this" action="add | remove" /> + </modify-argument> + + In the ``index`` argument you must specify the parent argument. The action + *add* creates a parent link between objects, while *remove* will undo the + parentage relationship. |