cannot use class with formstyle=callback (w/ possible solution)

[André Kablu]

I was creating a new formstyle, and I wanted to pass more details:

SQLFORM(db.table, formstyle=style(placeholder=True, errors='down'))

The idea was to create a class that receives both parameters then the __call__ method receives form and field parameters from sqlhtml createform.

I use a similar idea on the REQUIRES and REPRESENT callbacks.

Well, there is a line code there for backward compatibility:

args, varargs, keywords, defaults = inspect.getargspec(formstyle)

This creates an error b/c the inspect cannot capture __call__ from class.

The possible solution (worked for me) is:

            def get_callable_argspec(fn):

                if inspect.isfunction(fn) or inspect.ismethod(fn):

                    inspectable = fn

                elif inspect.isclass(fn):

                    inspectable = fn.__init__

                elif hasattr(fn, '__call__'):

                    inspectable = fn.__call__

                else:

                    inspectable = fn

                return inspect.getargspec(inspectable)

            args, varargs, keywords, defaults = get_callable_argspec(formstyle)

I think this is the best idea, if you guys have any commend or better idea please share.

Thanks!

[Anthony]

+1

[Leonel Câmara]

This would work but I have to say using a class for this feels very Javaish.

Python has closures. If you wanted to have arguments for your callback you could have easily put it inside another function with your arguments.

def make_formstyle(placeholder=True, errors='down'):

    

    def callback(form, fields):

        if placeholder:

            #do some stuff

      ....

    return callback

And then you would do

SQLFORM(db.table, formstyle=make_formstyle(placeholder=True, errors='down'))

That said, formstyle should definitely accept any callable but I hate all this inspection which is very unpythonic, maybe a better way would be to try to find a smarter way to do the backwards compatibility stuff. Instead of using inspect maybe we could just use a try and except. If it failed to call formstyle using the new 2 arguments way, then use the 4 arguments oldstyle. 

[Massimo DiPierro]

I agree. I am reverting the previous patch.

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