[Python-Dev] PEP 3101: Advanced String Formatting (original) (raw)

Georg Brandl g.brandl at gmx.net
Sun Apr 30 20:00:49 CEST 2006

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

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