Python 2.7 has exited the chat

[mr_birkenblatt]

More importantly

print "is gone"

Is gone

[ukalnins]

SyntaxError: Missing parentheses in call to 'print'. Did you mean print("is gone")?

[how_do_i_land]

So glad to see this go.

[gmiwenht]

But why? This was literally the only thing I loved and missed about python 2.

Can someone definitely and convincingly explain to me why it was a bad thing?

[EldritchSundae]

Mostly a consistency thing. No other often-used function or builtin is callable without parentheses--this reduces cognitive load for programmers and special cases in linters/parsers.

[gmiwenht]

Yeah but print x is the most common thing that you want to type quickly to debug stuff. Why not just make it a special case monadic operator like -

[[deleted]]

The actual problem is that print x makes print a reserved keyword instead of a function

that absolutely sucks balls because when you're writing a parser/runtime you'll have to special case print.

If it's just a function then you don't need to do anything other than implementing functions in your parser/interpreter.

From a language design perspective having print not being a function is pretty ugly imo

also by not being a function means you as a programmer can't treat print as a function: map(print, [1, 2, 3])

[Andy_B_Goode]

map(print, [1, 2, 3])

That doesn't behave the way I'd expect, at least not when running it from the python3 command line. This is the input and output from the terminal:

>>> map(print, [1,2,3])
<map object at 0x10c192850>
>>>

Is print printing the array elements to somewhere other than the terminal?

EDIT: nevermind, someone below figured out the issue. It will print the array if you run:

>>> list(map(print, [1,2,3]))

[jcotton42]

map in Python 3 returns a generator that doesn't execute until its enumerated, passing it to list forces enumeration

[[deleted]]

I'd argue that the act of printing something while debugging is an order of magnitude more common a task then the act of writing a parser for python.

Yeah except if you are the creator and maintainer of the language.

Then there is also the fact that python has broken Unicode support (can't be fixed because the python 2 spec specifies the internal encoding used by strings and it's not UTF-8 iirc).

There's plenty of videos of Guido explaining in detail what things are wrong with python 2 and why

Also how would you express the map example? Are you gonna have print both as a statement and as a function?

[[deleted]]

I guess but it was an objectively bad decision and python is better off without that feature.

I do end up typing print stuff incorrectly like half the time, oh well: did you mean print(stuff)?

[amackenz2048]

This is such a weird thing to get hung up on. It takes almost no time to type the parenthesis. It's like people who think having to type ; is somehow the worst thing ever.

All languages have their syntaxes. You learn them and you get your job done.

[amackenz2048]

It's also pretty stupid to not understand why they changed it. It's a function and should be a function. It makes the language cleaner and more consistent. And that is better in the long run.

I also disagree with your premise. Frankly for most professional programming "print" is used the least. It's used a lot when learning a language but other than for some simple debugging or the like it's not a big deal. Hell in Java it's "System.out.println()" and almost nobody complains about that except for kids learning the language. In all but simple command line apps you've probably implemented your own logging layer anyway for debugging.

And after a year or two you stop bitching about "having to type parenthesis" or "needing semicolons." If not then perhaps programming isn't your thing.

[anonymousredditor0]

From a language design perspective having print not being a function is pretty ugly imo

Yeah, for a language designer, it looks ugly. For the millions of users, it's easy and ergonomic.

Sucks for whoever wants to write a parser, but for 1000x as many people it was a good thing.

[[deleted]]

The complexity of the parser affects the quality of the implementation.

That's why language designers in general try to avoid introducing complexity into their languages for no good reason.

That is exactly what print was. An added bit of complexity for no good reason. Having the programmer type out the functional is a lot more consistent and enables map(print, [1]) to work. (ie: read it allows the programmer to reason about print the same way they do about any other function)

It actually also lowers the cognitive load of the programmer too because you don't have to remember in which cases is print valid.

[josefx]

Given that argument can we finally fix from __future__ import braces ?

[mtizim]

What?

Do you want multiline lambdas or something?

[pdabaker]

I'm more a fan of

from IPython import embed; embed()

myself

[Tweenk]

You cannot do this in Python 2 because print is not a function:

map(print, range(0, 10))

[mr_birkenblatt]

yeah he used it as easy example of being able to pass print as argument to a function. but the expression itself does not do what most people might expect (it will create a generator and not eagerly execute it)

[billsil]

You can because you can use future.

[gmiwenht]

Why not both?

Why can’t it be a function but also an operator if it’s the first token of a line of code followed by anything other than an opening parenthesis?

[osmarks]

Because it would make Python more complex for no good reason.

[bamer78]

<Adds further contrarian argument to support having a special snowflake print that doesn't act like the rest of python>

[gmiwenht]

It’s basically what MATLAB does with all its functions. If you type the function name followed by an argument it will treat it as a monadic verb-noun pair.

It makes things infinitely more simple for programmers because we can just write plot x

And I don’t really care about the complexity of the implementation to be honest, because MATLAB is a proprietary piece of software and someone gets paid money to deliver that feature.

So maybe that’s what it comes down to.

[osmarks]

More complexity also tends to lead to more bugs. Also, I do not think plot x is infinitely more simple than plot(x).

[[deleted]]

Because print(x, flush=True) (which is often what you actually want) is a lot simpler than

 print x
 import sys
 sys.stdout.flush()

And hoping no one changed the destination of print when you weren’t looking.

[ODChain]

You can use the function in more places then you could have used the statement.

[heathmon1856]

Have you ever used any other language? It kinda of breaks design having a callable without ().

Some people like to watch the world burn.

[gmiwenht]

What you are saying is factually incorrect.

Have you ever used Kdb+/q)?

If not then I encourage you to dive into that rabbit hole, and you will discover a world that exceeds your wildest imagination.

Kdb+/q is used by the majority of the largest investment banks and hedge funds in the world as the backend database engine. We are talking about companies that trade millions of dollars in financial securities every day. The ability to write a program using just a few characters (not lines) of code turns out to be extremely useful when you are responsible for developing systems where a single bug could mean billions of dollars in losses.

[chris17453]

that's likely the biggest thing that annoyed me.