type of LiteralInput does not work with pn.Param

[MarcSkovMadsen]

I would like to use a LiteralInput as the widget in pn.Param of a Parameterized class but it is not possible.

As type provides the type of widget in the below pn.Param example the type of a LIteralInput cannot be provided.

import param
import panel as pn
pn.extension()

WIDGETS = {
    "a_literal": {
        "type": pn.widgets.LiteralInput, "sizing_mode": "fixed", "width": 400, "placeholder": "Input a dictionary!"
    }
}

class ParameterizedApp(param.Parameterized):
    a_literal = param.Dict(default=None, label="A Dictionary")
    view = param.Parameter()
    
    
    def __init__(self, **params):
        super().__init__(**params)
        
        self.view = pn.Param(self, parameters=["a_literal"], widgets=WIDGETS)
        
parameterized_app = ParameterizedApp()
parameterized_app.view

So I can input a list even though the parameter is a dict.

[MarcSkovMadsen]

and ... this is of course not possible

import param
import panel as pn
pn.extension()

WIDGETS = {
    "a_literal": {
        "type": pn.widgets.LiteralInput, "sizing_mode": "fixed", "width": 400, "placeholder": "Input a dictionary!", "type": dict
    }
}

class ParameterizedApp(param.Parameterized):
    a_literal = param.Dict(default=None, label="A Dictionary")
    view = param.Parameter()
    
    
    def __init__(self, **params):
        super().__init__(**params)
        
        self.view = pn.Param(self, parameters=["a_literal"], widgets=WIDGETS)
        
parameterized_app = ParameterizedApp()
parameterized_app.view

----------------------------------------------------------------
AttributeError                 Traceback (most recent call last)
<ipython-input-5-bbb4723617e4> in <module>
     19         self.view = pn.Param(self, parameters=["a_literal"], widgets=WIDGETS)
     20 
---> 21 parameterized_app = ParameterizedApp()
     22 parameterized_app.view

<ipython-input-5-bbb4723617e4> in __init__(self, **params)
     17         super().__init__(**params)
     18 
---> 19         self.view = pn.Param(self, parameters=["a_literal"], widgets=WIDGETS)
     20 
     21 parameterized_app = ParameterizedApp()

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in __init__(self, object, **params)
    182             'object', 'parameters', 'name', 'display_threshold', 'expand_button',
    183             'expand', 'expand_layout', 'widgets', 'show_labels', 'show_name'])
--> 184         self._update_widgets()
    185 
    186     def __repr__(self, depth=0):

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in _update_widgets(self, *events)
    240             self._widgets = {}
    241         else:
--> 242             self._widgets = self._get_widgets()
    243 
    244         alias = {'_title': 'name'}

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in _get_widgets(self)
    502         else:
    503             widgets = []
--> 504         widgets += [(pname, self.widget(pname)) for pname in self._ordered_params]
    505         return OrderedDict(widgets)
    506 

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in <listcomp>(.0)
    502         else:
    503             widgets = []
--> 504         widgets += [(pname, self.widget(pname)) for pname in self._ordered_params]
    505         return OrderedDict(widgets)
    506 

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in widget(self, p_name)
    370                 kw['step'] = p_obj.step
    371 
--> 372         kwargs = {k: v for k, v in kw.items() if k in widget_class.param}
    373 
    374         if isinstance(widget_class, Widget):

c:\repos\private\panel-extensions-template\.venv\lib\site-packages\panel\param.py in <dictcomp>(.0)
    370                 kw['step'] = p_obj.step
    371 
--> 372         kwargs = {k: v for k, v in kw.items() if k in widget_class.param}
    373 
    374         if isinstance(widget_class, Widget):

AttributeError: type object 'dict' has no attribute 'param'