[Zope] Why is it so hard to do simple things?

[Chris McDonough]

Whoops.  I had it wrong last time around.  One more time, with feeling:

  <dtml-let button_value="REQUEST.get('perm_or_temp', 'P')">
     <INPUT TYPE='RADIO'
            NAME=perm_or_temp
            VALUE="P"
            <dtml-if "button-value=='P'">
            CHECKED</dtml-if>
            > Permanent
     <INPUT TYPE='RADIO'
            NAME=perm_or_temp
            VALUE="T"
            <dtml-if "button-value=='T'>
            CHECKED</dtml-if>
            > Temporary
  </dtml-let>

.. or ..

button_value = context.REQUEST.get('perm_or_temp', 'P')
possible = {'P':'Persistent','T':'Temporary'}
items = possible.items()
items.sort()
for key, value in items:
     checked = (key == button_value) and ' CHECKED' or ''
     print ("<input type=radio name=perm_or_temp VALUE='%s'%s> %s" %
            (key, checked, value))
return printed

.. and a bonus alternate DTML implementation mirroring the Python one ..

  <dtml-let button_value="REQUEST.get('perm_or_temp', 'P')"
            possible="{'P':'Persistent','T':'Temporary'}"
            items="possible.items()">
  <dtml-call "items.sort()">
  <dtml-in items>
    <dtml-let "checked = (_[sequence-key] == button_value) and ' 
CHECKED' or ''>
       <INPUT TYPE='RADIO'
             NAME=perm_or_temp
             VALUE="<dtml-var sequence-key>"
             <dtml-var checked>> <dtml-var sequence-item>
    </dtml-let>
  </dtml-in>
  </dtml-let>

Chris McDonough wrote:
> John Adams wrote:
> 
>> If I was doing this in perl it'd be quite easy; I could check the query
>> variable, and act on it -- but now I have to deal with things like not
>> being able to even examine the variable without throwing an exception, 
>> and
>> the fact that Python doesn't short-circuit blows.
>>
>> i.e. You can't examine something like:
>>
>> if (hasattr(request,'perm_or_temp') and request.perm_or_temp == 'P')
> 
> 
> Python does indeed short-circuit this statement and it will work as you 
> seem to expect.  Have you tried it?
> 
> In DTML, here is something that will do what I think you want.
> 
> <dtml-let button_value="REQUEST.get('perm_or_temp')">
>    <INPUT TYPE='RADIO'
>           NAME=perm_or_temp
>           VALUE="P"
>           <dtml-if "button-value=='P' or button_value==None">
>           CHECKED</dtml-if>
>           > Permanent
>    <INPUT TYPE='RADIO'
>           NAME=perm_or_temp
>           VALUE="T"
>           <dtml-if "button-value=='T'>
>           CHECKED</dtml-if>
>           > Temporary
> </dtml-let>
> 
> There's a million variations on this, some better than others.  In 
> Python one way to do this would be as:
> 
> button_value = context.REQUEST.get('perm_or_temp')
> checked_button = {None: 'P', 'P':'P', 'T':'T'}.get(button_value)
> for value in ['P', 'T']:
>     checked = (value == checked_button) and ' CHECKED' or ''
>     print ("<input type=radio name=perm_or_temp VALUE='%s'%s>" %
>            (value, checked))
> return printed
> 
> You could do something similar to this in DTML if you wanted as well. 
> Since there are only a couple of possible values, it's probably easier 
> just to spell it all out in this case.
> 
> I'd suggest picking up the "Learning Python" O'Reilly book to learn 
> basic idioms like this.  The thing you were missing was that 
> dictionary-like objects (of which REQUEST is one) have a get method that 
> returns None if nothing of that key exists in the dictionary on a lookup.
> 


-- 
Chris McDonough                    Zope Corporation
http://www.zope.org             http://www.zope.com
"Killing hundreds of birds with thousands of stones"