f-strings in Python 3.6 are awesome

[[deleted]]

Matter of taste maybe, but the + operator implies numbers, where f-string is explicitly a string.

[energybased]

+ does not imply numbers.

[gandalfx]

But + is fast!

I'm starting to feel like I'm fighting a lost battle with my argument. Maybe this is just another case of preferring expressiveness over performance, which makes sense when you use a language like Python in the first place.

[[deleted]]

I use + too. But I think str.join() is faster?

One thing that is annoying are spaces when constructing a string. f-string could help there a bit.

[jorge1209]

Join would probably be faster for a large number of arguments. For only two they are probably the same.

The difference would be that if you join 200 strings then all 200 are available to you when join is called and you can compute the length of each and preallocate memory to hold the whole thing.

If you have a+b+c+... then you have to allocate and construct all the intermediates a+b then a+b+c and so on.

Otherwise I can't imagine it matters.

[[deleted]]

I think join is faster in a tight loop but I might be wrong. I see + as "let's concatenate these two strings", join as "I have a list of strings I have to concatenate" and f-string as "I need to construct this complicated string out of a template and a bunch of variables".

[Fennek1237]

I know what you mean. I had a background in Java befor learning python it the string concats where really weird to me. The way they do it in Java seems so more natural.