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From: Peter Otten <__peter__@web.de>
Subject: Re: raw format string in string format method?
Date: Thu, 28 Feb 2013 16:41:54 +0100
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Xref: csiph.com comp.lang.python:40134

Helmut Jarausch wrote:

> I'd like to print a string with the string format method which uses
> {0}, ...
> 
> Unfortunately, the string contains TeX commands which use lots of
> braces. Therefore I would have to double all these braces just for the
> format method which makes the string hardly readable.
> 
> Is there anything like a "raw" format string and any other means
> to circumvent this?
> 
> Many thanks for a hint,
> Helmut.

While percent-formatting is probably the way to go here is a hack to replace 
the braces with custom characters:

import string

class SwapFormatter(string.Formatter):
    custom = "<>"
    braces = "{}"
    swap = {ord(p): q for p, q in zip(custom + braces, braces + custom)}

    def format(self, format_string, *args, **kw):
        format_string = format_string.translate(self.swap)
        return super().format(format_string, *args, **kw)

    def parse(self, format_string):
        return ((t[0].translate(self.swap),) + t[1:]
                for t in super().parse(format_string))

myformat = SwapFormatter().format
print(myformat("<< {} {{<0>}} <2> {<foo>} <1:<width>> >>",
               "alpha", 42, "gamma", foo="delta", width=5))