attribute library documentation edits

This commit is contained in:
William S Fulton 2022-02-05 20:33:16 +00:00
parent aef4a0f90a
commit 34d80dcb8b
3 changed files with 60 additions and 47 deletions

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@ -449,6 +449,7 @@
<li><a href="Library.html#Library_nn16">Utility Libraries</a>
<ul>
<li><a href="Library.html#Library_nn17">exception.i</a>
<li><a href="Library.html#Library_attributes">attribute.i</a>
</ul>
</ul>
</div>

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@ -44,7 +44,7 @@
<li><a href="#Library_nn16">Utility Libraries</a>
<ul>
<li><a href="#Library_nn17">exception.i</a>
<li><a href="#Library_Attributes">attribute.i</a>
<li><a href="#Library_attributes">attribute.i</a>
</ul>
</ul>
</div>
@ -2109,9 +2109,14 @@ For example:
</div>
<H3><a name="Library_Attributes">12.5.2 attribute.i</a></H3>
<H3><a name="Library_attributes">12.5.2 attribute.i</a></H3>
<p>
The attribute library contains a set of macros to convert a pair of set/get methods
into a "native" attribute/property.
</p>
<p>
Use <tt>%attribute</tt> when you have a pair of get/set methods to a
primitive type like:
@ -2122,8 +2127,7 @@ primitive type like:
%include "attribute.i"
%attribute(A, int, a, get_a, set_a);
struct A
{
struct A {
int get_a() const;
void set_a(int aa);
};
@ -2132,8 +2136,21 @@ struct A
<p>
and you want to provide that variable as an attribute in the target
langage. This examples only works for primitive types, not derived
types. If you don't provide a 'set' method, a 'read-only' attribute
langage. This example only works for primitive types, not derived
types.
Now you can use the attributes like so (in Python):
</p>
<div class="targetlang">
<pre>
x = A()
x.a = 3 # calls A::set_a(3)
print(x.a) # calls A::get_a() const
</pre>
</div>
<p>
If you don't provide a 'set' method, a 'read-only' attribute
is generated, ie, like:
</p>
@ -2152,21 +2169,31 @@ access methods for primitive types or class/structs, like:
<pre>
%attributeref(A, int, b);
struct A
{
const int& b() const;
int& b();
struct A {
const int &amp; b() const;
int &amp; b();
};
%attributeref(B, int, c);
struct B
{
int& c();
struct B {
int &amp; c();
};
</pre>
</div>
<p>
Use the attributes like so (in Python):
</p>
<div class="targetlang">
<pre>
x = A()
x.b = 3 # calls A::b()
print(x.b) # calls A::b() const
</pre>
</div>
<p>
You can also use
</p>
@ -2193,25 +2220,10 @@ is the same as the last example, but instead of the attribute 'c' being
called 'c', it is called 'd'.
</p>
<p>
Now you can use the attributes like so:
</p>
<div class="code">
<pre>
x = A()
x.a = 3 # calls A::set_a
print x.a # calls A::get_a
x.b = 3 # calls A::b()
print x.b # calls A::b() const
</pre>
</div>
<p>
Use <tt>%attribute2</tt> instead of <tt>%attribute</tt> to indicate
that reference-pointer translation is required. You
use <tt>%attribute2</tt> instead of <tt>%attribute</tt> in cases like
that reference-pointer translation is required.
Use <tt>%attribute2</tt> instead of <tt>%attribute</tt> in cases like
this:
</p>
@ -2225,18 +2237,18 @@ this:
class MyClass {
MyFoo foo;
public:
MyFoo& GetFoo() { return foo; }
void SetFoo(const MyFoo& other) { foo = other; }
MyFoo &amp; GetFoo() { return foo; }
void SetFoo(const MyFoo &amp;other) { foo = other; }
};
%}
</pre>
</div>
<p>
Here, the data type of the property is a wrapped type (MyFoo) and on
Here, the data type of the property is a wrapped type <tt>MyFoo</tt> and on
the C++ side it is passed by reference. The problem is that the SWIG
wrapper will pass around a pointer (MyFoo *) which is not compatible
with the reference type of the accessors (MyFoo &). Therefore, if you
with the reference type of the accessors (MyFoo &amp;). Therefore, if you
use <tt>%attribute</tt>, you'll get an error from your C/C++
compiler. <tt>%attribute2</tt> translates between a pointer and a
reference to eliminate the error. In case you're confused, let's make
@ -2247,12 +2259,12 @@ try <tt>%attribute2</tt> instead.
<p>
NOTE: remember that if the type contains commas, such as
'std::pair<int,int>', you need to use the macro like:
<tt>std::pair&lt;int, int&gt;</tt>, you need to use the macro like:
</p>
<div class="code">
<pre>
%attributeref(A, %arg(std::pair<int,int>), pval);
%attributeref(A, %arg(std::pair&lt;int, int&gt;), pval);
</pre>
</div>
@ -2275,10 +2287,10 @@ access is by value rather than reference.
%attributeval(MyClassVal, MyFoo, ReadOnlyFoo, GetFoo);
%inline %{
class MyClassVal {
MyFoo foo;
MyFoo foo;
public:
MyFoo GetFoo() { return foo; }
void SetFoo(MyFoo other) { foo = other; }
MyFoo GetFoo() { return foo; }
void SetFoo(MyFoo other) { foo = other; }
};
%}
</pre>
@ -2288,21 +2300,21 @@ access is by value rather than reference.
The <tt>%attributestring</tt> is the same as <tt>%attributeval</tt>,
but should be used for string class types, which are unusual as they
are a class on the C++ side, but normally an immutable/primitive type
in the target language. Example usage for std::string:
in the target language. Example usage for <tt>std::string</tt>:
</p>
<div class="code">
<pre>
%include <std_string.i>
%include &lt;std_string.i&gt;
%attributestring(MyStringyClass, std::string, ReadWriteString, GetString, SetString);
%attributestring(MyStringyClass, std::string, ReadOnlyString, GetString);
%inline %{
class MyStringyClass {
std::string str;
std::string str;
public:
MyStringyClass(const std::string &val) : str(val) {}
std::string GetString() { return str; }
void SetString(std::string other) { str = other; }
MyStringyClass(const std::string &amp;val) : str(val) {}
std::string GetString() { return str; }
void SetString(std::string other) { str = other; }
};
%}
</pre>
@ -2312,7 +2324,7 @@ in the target language. Example usage for std::string:
The <tt>%attributestring</tt> also works for class types that
have <tt>%naturalvar</tt> turned on and so is also useful for
shared_ptr which has <tt>%naturalvar</tt> turned on in
<tt>%shared</tt>_ptr.
<tt>%shared_ptr</tt>.
</p>

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@ -2776,7 +2776,7 @@ void Foo_w_set(FOO *f, WORD value) {
<p>
If you have accessor methods that you want to use as attributes in the
target language, you can make them appear as data members using
<a href="Library.html#Library_Attributes">attributes.i</a>.
<a href="Library.html#Library_attributes">attributes.i</a>.
</p>
<p>