[Tutor] To FORMAT or not to

[Francois Dion]

And as Chris points out, if there is any possibility that the words will be
in a different order in a different language, use {0}, {1} instead of {}.


Francois

On Sun, Jan 3, 2016 at 8:04 AM, Chris Warrick <kwpolska at gmail.com> wrote:

> On 3 January 2016 at 13:27, yehudak . <katye2007 at gmail.com> wrote:
> > Hi there,
> > In a program I wrote the following line (Python 3.5):
> >
> > print("You've visited", island, '&', new + ".")
> >
> > A programmer told me that it's a bad habit, and I should have used
> instead:
> >
> > print("You've visited {0} {1} {2}{3}".format(island, "&", new, "."))
> >
> > May I understand why?
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> The programmer was not very intelligent in his use of str.format in
> the first place. A more sensible way to write this is:
>
> print("You've visited {0} & {1}.".format(island, new))
>
> Formatting with constant strings is pointless, just include it in the
> original input. However, string formatting is not.
>
> Here are a couple of reasons:
> * String formatting works everywhere, but this syntax is specific to
> print() — if you use something else, you might end up producing faulty
> code
> * The corrected string formatting usage is more readable than the
> original print()
> * String concatenation with + requires that all arguments are strings,
> which is even less readable
> * With string formatting, you can apply special formatting to your
> inputs (eg. set width, number precision…), which is hard or impossible
> with print()
> * Using print() with commas adds spaces between all entries, which
> might look bad (and it does in this example); the only way to prevent
> that is by setting `sep=`, but then you need to remember about a space
> after "visited" and around the ampersand…
> * Easy to localize (translate into different languages), which is
> generally impossible with any of the other options (some languages
> might rearrange the sentence!)
>
> --
> Chris Warrick <https://chriswarrick.com/>
> PGP: 5EAAEA16
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