On 2023-04-28 15:25, Matsuoka Takuo wrote:
What if it's done not by format method but by a separete method, say, format_partially or something? The method is different from format also in that it should leave "{{" and "}}" unaltered.
On Fri, 28 Apr 2023 at 00:05, Matthias Görgens <matthias.goergens@gmail.com> wrote:
Does it have any use case that's not already served by functools.partial?
I guess you mean given
partially_formatted_string = unformatted_string.format(color="blue")
that
partially_formatted_string.format
would be equivalent to
partial(unformatted_string.format, color="blue")
However, I think a partially formatted string can help since it will have other methods than format as well. For instance, given
unformatted_string = '{color}{text}'
doing the following thing only with functools.partial could require more care than you would be willing to give.
string = (unformatted_string.format(color="blue") + unformatted_string ).format(text="Spanish", color="red")
(One of the easiest ways might be
``` from functools import partial from operator import call
format_ = unformatted_string.format string = "".join(map(partial(call, text="Spanish"), (partial(format_, color="blue"), partial(format_, color="red"), ))) ```
However, note the following, more straight-forward code doesn't work:
``` string = "".join(map(partial(call, text="Spanish", color="red"), (partial(format_, color="blue"), format_, ))) ``` )
Now, how about this?
``` format_ = '{a}{b}{c}'.format
string = ((format_(a=a0) + format_(b=b0)).format(c=c0) + (format_(a=a1) + format_(c=c1)).format(b=b1) + (format_(b=b2) + format_(c=c2)).format(a=a2) ).format(a=a3, b=b3, c=c3) ```
(For instance, the following code fails:
``` from itertools import chain
string = "".join(map(partial(call, a=a3, b=b3, c=c3), chain.from_iterable( map(map, (partial(partial, c=c0), partial(partial, b=b1), partial(partial, a=a2), ), ((partial(format_, a=a0), partial(format_, b=b0), ), (partial(format_, a=a1), partial(format_, c=c1), ), (partial(format_, b=b2), partial(format_, c=c2), ), )) ))) ``` )
What happens if you do '{open}...{close}'.partial_format(open='{close}'? You get '{close}...{close}', and you're going to have a problem using that as a format string and replacing only the second '{close}'. Or how about '{open}...{close}'.partial_format(open='{')? You get '{...{close}'. Try using that as a format string! That's why I think that the result of a partial format should be an instance of a new class and not a string.