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Comment by dec0dedab0de | Hacker News Reader

my favorite cheat is using locals() with string formatting something like this:

  def example_cheater(color, flavor, age):
    
      template = 'I am {age} years old and I like to wear {color} hats and eat {flavor} icecream'
      return template.format(**locals())

Obviously a contrived example, and it can be argued that using locals() is not very pythonic, but I think it makes the code look much nicer.

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In python 3.6 and up, that becomes

    def example_cheater(color, flavor, age):
      return f'I am {age} years old and I like to wear {color} hats and eat {flavor} icecream'

Even nicer!

For reference, this feature is Formatted String Literals ("f-strings"). https://docs.python.org/3/reference/lexical_analysis.html#fo...

Of course I didn't read your comment until several Google searches later.

Didn't know this. Thanks for sharing!

OMG! that is so exciting, Thank you for telling me! I have only been using 3.x as my primary language for a few months now, I can't wait to try this out. I feel like a huge dork right now, because that made my day.

Does this trip up pylint?

Hasn’t for me.

Trips up Vim's syntax highlighter.

Taken straight out of Ruby, I see. Very convenient feature (and one of my favorites about Ruby), though it does contradict the do-it-one-way mentality.

According to Rosetta Code Algol 68 had string interpolation. [1]

It'd be interesting to see if there are any older languages that supported it too.

https://rosettacode.org/wiki/String_interpolation_(included)...

>though it does contradict the do-it-one-way mentality.

not really: use f-strings when you're passing in variables as-is (or nearly no work), and format() when you need to do work on them before stringifying them; f-strings are naturally (and obviously) more difficult to read when the variables are big, as it obscures the actual text they're being fit into, and where.

The only natural area for preference to apply is whether to do the work before the format() call, name the variables, and change it to an f-string.. or stick with a multi-line format()

I'm not sure theres any real situation where the choice isn't obvious. Maybe if you're doing something like f"list1: {sorted(a)}\nlist2{sorted(b)}", where the work is rather small, but even then f"list1:{}\nlist2:{}".format(sorted(a), sorted(b)) is just as nice, or rather unsatisfying, as the f-string.

f-strings are also unusable for i18n.

> not really:

Yes it does. You could construct the string using a for-loop. Thank you for proving my point and then down-voting me.

...if you’re going down that route, you could claim that any feature not necessary for turing completeness conflicts with the one way to do it strategy, since you could alternatively build up whatever feature from scratch, thus offering additional solutions

But practically, there remains (close to) one obvious way to do things, with the choice boiling down to whether or not to name your outputs before string construction (and the choice of f-string vs format naturally falling out). But thats always been a choice.

On a side note: I don’t use comment voting systems, for up or down votes, on pretty much any site including HN. Even if I did, I don’t see why you’d care

> if you’re going down that route, you could claim that any feature not necessary for turing completeness conflicts with the one way to do it strategy

I suppose one could do that, philosophically if not practically. What I had in mind was the various syntax sugars used for the same thing, particularly in Ruby. While some ways of doing things in Ruby were convenient, there was a host of other "shortcuts" that added to the confusion, and it was evident that it was the design of the language itself - not an accident - that allowed these shortcuts, at least imo.

> On a side note: I don’t use comment voting systems

I had a feeling you might say that, but I'd already clicked the "reply" button. Sorry for being presumptuous.

Not that I care about the voting system either, but people tend to use it as a cowardly way of showing disapproval.

Neat:

    >>> pi = 3.14159; two = 2
    >>> f"{two:02d} pi is {2*pi:.2f}"
    '02 pi is 6.28'

My favorite unpacking snippet is rotating a matrix

>>> matrix = [(1,2,3),(4,5,6),(7,8,9)]

>>> list(zip(*matrix))

[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

Not as readable as a real maths library, but pretty cool and educational.

Think I came across it in Python in a nut shell, by Alex Martelli

Edit: formatting

My frustration with locals() and globals() is the same with "from foo import *" It's really difficult to move that code around or clean up variables because their use is obscured. The worst is when your template variable is defined somewhere else.

Calling calling a Python standard library function "not pythonic" is a great example of when the term "pythonic" is beyond usefulness.

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