Re: [Jython-users] Multiple constructor signatures

[Robert W. B. <rb...@di...>]

Hi John,

On Fri, 31 Aug 2001, John Goerzen wrote:
> Hi,
>
> I'm trying out Jython for the first time but the documentation have
> not covered this scenario:
>
> I want to make a class that is callable by Java, that is a child only
> of java.lang.Object, whose constructor can take 0 or 1 arguments.
>
> There seems to be no way to specify two @sig lines.

True, but jythonc doesn't require multiple sigs.

> import java
>
> class Foo(java.lang.Object):
>     def __init__(self, arg=None):
>         """@sig public Foo()
>            @sig public Foo(String arg)"""
>         if arg:
>             print arg
>         else:
>             print "No arg passed"

You don't need multiple @sigs, jythonc figures it out for you.  In your
code example, the only @sig you need is "@sig public Foo(String arg)". If
you take a peek at Foo.java, you will see that you also get an empty
constructor for free.

Additionally, if you have two default args, jythonc adds constructors
for no args, 1 arg, and 2 args.

for example:

import java

class Foo(java.lang.Object):
    def __init__(self, arg1=None, arg2=None):
        "@sig public Foo(String arg1, String arg2)"
        print arg1, arg2


With that one @sig string, you can call the constructors from Java:

    test t = new test();
    test t = new test("bar");
    test t = new test("bar", "zab");



-rb