jyapayne/swig
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

A bit more docs.

Browse source 
git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@5341 626c5289-ae23-0410-ae9c-e8d60b6d4f22
This commit is contained in:
Dave Beazley 2003-11-18 22:45:48 +00:00
commit 2e79282dab
1 changed files with 70 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

72
SWIG/Doc/Manual/Contract.html
View file

@ -18,7 +18,7 @@ using it in a way that wasn't intended.
<p>
This chapter describes SWIG's support for software contracts. In the context
of SWIG, a contract can be viewed as a constraint that is attached
of SWIG, a contract can be viewed as a runtime constraint that is attached
to a declaration. For example, you can easily attach argument checking rules,
check the output values of a function and more.
When one of the rules is violated by a script, a runtime exception is
@ -68,13 +68,81 @@ resulting module. For example:
>>> example.sqrt(-2)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
RuntimeError: Require assertion violation, in function sqrt( arg1>=0)
RuntimeError: Contract violation: require: (arg1>=0)
>>>
</pre>
</blockquote>
<h2>%contract and classes</h2>
The <tt>%contract</tt> directive can also be applied to class methods and constructors. For example:
<blockquote>
<pre>
%contract Foo::bar(int x, int y) {
require:
x > 0;
ensure:
bar > 0;
}
%contract Foo::Foo(int a) {
require:
a > 0;
}
class Foo {
public:
Foo(int);
int bar(int, int);
};
</pre>
</blockquote>
The way in which <tt>%contract</tt> is applied is exactly the same as the <tt>%feature</tt> directive.
Thus, any contract that you specified for a base class will also be attached to inherited methods. For example:
<blockquote>
<pre>
class Spam : public Foo {
public:
int bar(int,int); // Gets contract defined for Foo::bar(int,int)
};
</pre>
</blockquote>
In addition to this, separate contracts can be applied to both the base class and a derived class. For example:
<blockquote>
<pre>
%contract Foo::bar(int x, int) {
require:
x > 0;
}
%contract Spam::bar(int, int y) {
require:
y > 0;
}
class Foo {
public:
int bar(int,int); // Gets Foo::bar contract.
};
class Spam : public Foo {
public:
int bar(int,int); // Gets Foo::bar and Spam::bar contract
};
</pre>
</blockquote>
When more than one contract is applied, the conditions specified in a
"require:" section are combined together using a logical-AND operation.
In other words conditions specified for the base class and conditions
specified for the derived class all must hold. In the above example,
this means that both the arguments to <tt>Spam::bar</tt> must be positive.
<h2>Constant aggregation and %aggregate_check</h2>