AmbiguousMethods exception for presentation tier

[Terrence Brannon]

I created two presentation models for instances of the class

BodyTextEditor. A default one:

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L359

and an edit one:

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L388

I had no problems before this. But now, my app is dying with the error:

"""

AmbiguousMethods: ([Method(<function render at 0x7f8f940c6ed8>,

Signature([Test(IsInstance(Local('self')), Class(<class

'obflparserui.app.BodyTextEditor'>, True)),

Test(IsInstance(Local('renderer')), Class(<type 'object'>, True)),

Test(IsInstance(Local('comp')), Class(<type 'object'>, True)),

Test(IsInstance(Local('model')), Class(<type 'NoneType'>, True))]),

115, None), Method(<function render at 0x7f8f940ca140>,

Signature([Test(IsInstance(Local('self')), Class(<class

'obflparserui.app.BodyTextEditor'>, True)),

Test(IsInstance(Local('renderer')), Class(<type 'object'>, True)),

Test(IsInstance(Local('comp')), Class(<type 'object'>, True)),

Test(IsInstance(Local('model')), Class(<type 'NoneType'>, True))]),

116, None)], (<obflparserui.app.BodyTextEditor object at

0x7f8f74bc69d0>, <nagare.namespaces.xhtml.Renderer object at

0x7f8f74bc6f50>, <component with default model at 0x7f8f74bc6a10 on

object <obflparserui.app.BodyTextEditor object at 0x7f8f74bc69d0>>,

None), {})

"""

the reason this is happening is on line 831 we see:

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L831

    h << self.body

and self.body is instantiated to a component.Component() instance

whose object is a BodyTextEditor() and whose presentation model is set

to None (hence the default one):

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L779

Therefore the default rendering method for BodyTextEditor on line 359

should be the obvious one to choose. But for some reason, nagare is

confused and thinks there is some possibility that the method on line

388 (the alternative presentation model named 'edit') could be a

candidate as well. Why is this?

[Terrence Brannon]

This problem still exists. I have a workaround. as I said, there are two presentation models for instances of the class

BodyTextEditor. A default one:

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L359

and an edit one:

https://gist.github.com/metaperl/9cf7b7106a856710bd71#file-gistfile1-py-L388

When the default one has a decorator like this:

@presentation.render_for(BodyTextEditor)

then the AmbiguousMethods exception is thrown.

When the default decorator looks like this:

@presentation.render_for(BodyTextEditor, model='normal')

then the program seems to work fine. But the default view in the Counter example does not have a model name added to it:

http://www.nagare.org/trac/browser/examples/nagare/examples/counter.py#L42

and it works just fine.

[Sylvain Prat]

Hi,

Your gist file show 2 different lines (359, 388) with:

@presentation.render_for(BodyTextEditor)

That's why you get an "ambiguous method" error message. How can nagare know which render function it should use when rendering the default view of a BodyTextEditor instance?

Sylvain

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Sylvain PRAT
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