What's your favorite language feature?

[mrflibble]

Thought it would be fun to hear from other people what cool language features are out there. What feature in your programming language of choice do you like the most? Can be anything about any language.

My choice would have to be ... mmmhh, list comprehension in python. Maybe generators in general. Oh and itertools, and, and... But to keep it specific, yes, list comprehension.

So what's yours?

[jfiresto]

Associative arrays (dictionaries), named arguments and coroutines

[tggzzz]

Hard realtime performance guaranteed by the IDE not measurement (combination of hardware and software), output to be executed at specified clock cycle, input received at a specified clock cycle. All found in xC running on xCORE processors

Built-in primitives (not libraries) for multiprocessor systems and inter-processor communication. Found in CSP, Occam, xC and to a lesser extent Rust and Go.

[Mechatrommer]

pointer, pointer to pointer, type casting, OOP, operator overloading. keen coder should already know what is this, only one language can provide this at humanly friendly language/syntax. the rest? list of <insert whatever here>, dictionary <insert your fav here> etc all can be made later on as a class or whatever (higher level function), but once the pointer feature is not available directly, it feels like sitting on a wheelchair losing both legs.

[AndyC_772]

Conditional execution, especially as applied to branch instructions.

[SiliconWizard]

Swearing and cursing. 

[jfiresto]

Swearing and cursing. 

Ah, but in what language?

[boffin]

• Associative Arrays/Dictionaries (most modern languages)
• Sets (Pascal).  Just wait until you use a set to represent an output register.  It's a thing of beauty....

[dferyance]

Separate compilation / linker.
So many "modern" programming languages don't bother with it (Java, .Net, Python, NodeJS). So you end up with Docker hell trying to manage all your dependencies.

A programming language ought to be able to produce a single executable without additional runtime libraries or installs. That isn't to say all applications should be a single executable, but they all ought to be able to use a linker to include dependencies (as well as exclude) at compile time.

[SiliconWizard]

Swearing and cursing. 

Ah, but in what language?

Any that supports it. The OP said: "Can be anything about any language."

[ve7xen]

I'm going to go with type inference as my favourite 'general' feature. It makes strongly typed languages so much nicer to use.

As for the 'coolest' feature, I'm going to go with Golang's goroutines and channels.

[tggzzz]

I'm going to go with type inference as my favourite 'general' feature. It makes strongly typed languages so much nicer to use.

As for the 'coolest' feature, I'm going to go with Golang's goroutines and channels.

Actually Communication Sequential Processes' channels and execution semantics. From 1976, from CAR Hoare. Look him up on wackypedia etc.

First implementation : Occam in the early 80s. Current variant: xC,  as per my previous post

[Nominal Animal]

Aggressive and words of power.

External language bindings in various programming languages, and extended inline assembly in GNU C and C++.

[bsudbrink]

I like languages that allow direct access to hardware, including the CPU and its registers.  And the operations are represented by simple numeric codes in consecutive memory locations.

[David Hess]

Sane casting of integer multiplies and divides would be my favorite language feature if it existed.

[I wanted a rude username]

The ternary operator.

[golden_labels]

Prototype-based programming. Easy to abuse, but great for compatibility layers and modifying method behaviour. Unfortunately also quite inefficient.
Any type of sane multiline string literals, possibly coupled with indentation removal.
Template metaprogramming in C++. Too bad the error messages are unreadable.
Null coalescing and Elvis operators, in various shapes and forms.

Separate compilation / linker.
So many "modern" programming languages don't bother with it (Java, .Net, Python, NodeJS). So you end up with Docker hell trying to manage all your dependencies.

A programming language ought to be able to produce a single executable without additional runtime libraries or installs. That isn't to say all applications should be a single executable, but they all ought to be able to use a linker to include dependencies (as well as exclude) at compile time.

Java has a separate compiler (javac) and “linker” (java).

Since Java has no executables, it also means the second paragraph would not apply. However: the closest it has to executables, JARs, allow you to pack anything you want — including all the dependencies. This is a horribly bad practice that will bite you just like any other failure at using modularity, but there is nothing that prevents you from doing so.

[ivaylo]

functions as first class citizens
in any language...

[emece67]

.

[jfiresto]

Closures

[SiliconWizard]

Template metaprogramming in C++. Too bad the error messages are unreadable.

I would cite metaprogramming in general as well. Unfortunately, this is so badly implemented in most languages I know of that I can't really associate this sanely with any.
C++ templates were a nice attempt at first, but they became horrible, and yes the diagnostic messages are usually unusable, so you better get it right first or you will cry.

Since Java has no executables, it also means the second paragraph would not apply. However: the closest it has to executables, JARs, allow you to pack anything you want — including all the dependencies. This is a horribly bad practice that will bite you just like any other failure at using modularity, but there is nothing that prevents you from doing so.

Java itself is a horribly bad practice.

[dferyance]

Java has a separate compiler (javac) and “linker” (java).

I intended to mean static or compile-time linker. Most languages and operating systems have some sort of dynamic linker.

Yeah, JAR is essentially a work-around, similar to Docker. It still is dynamic linking, slows down program startup, can fail for things that ought to be caught at compile time, doesn't eliminate dead-code or do link-time optimizations. But it is better than having a ton of files all over the place.

[TerminalJack505]

I would say that, in general, my favorite language feature is "being modern."  That is, a language that evolves to meet the demands of modern software engineering and doesn't rest on its laurels and live in the past.  A language that helps the developer apply best practices as they are understood here-and-now.  (I'm basically calling-out languages like 'C', here.)

Specifically, I'd say one of the most interesting language features to come (back) around recently is coroutines.

[IDEngineer]

Saw this thread and had to comment, since I just had to learn Python for a small side project....

You'll never realize how much you appreciate braces surrounding (read: clearly, unmistakably delimited) code blocks in C/C++, until you work in a language like Python where (invisible) (whitespace) indent levels attempt to substitute for them.

Whomever dreamt that up should be professionally embarrassed for eternity. No other accomplishment can possibly offset the lunacy of that decision.

EDIT: If we can take visible code block delimiters for granted, then my favorite language feature is pointers. Can't think of a single other feature that is as powerful and flexible. Can pointers be misused? Sure, just like any other powerful tool in any context. It's the wrong approach to cripple a language so you can better tolerate poor software authors. Hint: Poor software authors will always find ways to leave bugs in their code.

[SiliconWizard]

You'll never realize how much you appreciate braces surrounding (read: clearly, unmistakably delimited) code blocks in C/C++, until you work in a language like Python where (invisible) (whitespace) indent levels attempt to substitute for them.

Whomever dreamt that up should be professionally embarrassed for eternity. No other accomplishment can possibly offset the lunacy of that decision.

Ahah, I fully agree. This is wrong on so many levels, but one that's definitely worse than others is maintainability and code sharing.

More generally speaking, this is a pet peeve of mine actually: many people seem to be in the quest for minimizing the number of characters they have to type when writing code, and blame overly "verbose" languages. C is already pretty lean, but some people find it still too verbose and want to get rid of more signs like braces and parentheses.

I think this is completely dumb, and often say that if the number of characters you have to type to write a given piece of code really matters to you compared to all other design and implementation tasks, then the code you write must be either really simple or really lame.

Just my 2 cents.