[Python-Dev] PEP 3101: Advanced String Formatting

[Georg Brandl]

Zachary Pincus wrote:
> I'm not sure about introducing a special syntax for accessing  
> dictionary entries, array elements and/or object attributes *within a  
> string formatter*... much less an overloaded one that differs from  
> how these elements are accessed in "regular python".

Yes, I also think that's a bad idea.

>>      Compound names are a sequence of simple names seperated by
>>      periods:
>>
>>          "My name is {0.name} :-\{\}".format(dict(name='Fred'))

And these escapes are also a bad idea. As it is, the backslashes stay in the
string, but it is not obvious to newcomers whether \{ is a general string
escape. The "right" way to do it would be "\\{", but that's becoming rather
longly. Why not use something like "{{"?

>>      Compound names can be used to access specific dictionary entries,
>>      array elements, or object attributes.  In the above example, the
>>      '{0.name}' field refers to the dictionary entry 'name' within
>>      positional argument 0.
> 
> Barring ambiguity about whether .name would mean the "name" attribute  
> or the "name" dictionary entry if both were defined, I'm not sure I  
> really see the point. How is:
>    d = {last:'foo', first:'bar'}
>    "My last name is {0.last}, my first name is {0.first}.".format(d)
> 
> really that big a win over:
>    d = {last:'foo', first:'bar'}
>    "My last name is {0}, my first name is {1}.".format(d['last'], d 
> ['first'])

Or even:

d = {last:'foo', first:'bar'}
"My last name is {last}, my first name is {first}.".format(**d)

Georg