5 ms·

I wish they didn't! Magic features like this belong to magic languages like Ruby. Go is not meant to be a magic language.

thescrewdriver 13y ago
Go is designed to be a very practical and productive language. It's not quite clear how you're defining "magic" ... String interpolation is both practical and useful.
- DrJokepu 13y ago
  String interpolation is magic because it's not entirely obvious when it happens, what scope rules are followed, if there are any side effects, if the original string is overwritten or whether a new instance is created, what happens when they are used within bodies of loops, what happens when they are used within closures etc., it just works. Sure these can be specified explicitly but they aren't obvious. It's the kind of feature that is useful when you write an application but not that useful when you're trying to debug it.
  - thescrewdriver 13y ago
    > It's the kind of feature that is useful when you write an application but not that useful when you're trying to debug it. It's largely used in log messages and the like where it's used for debugging issues after the fact. I've yet to encounter a case where anyone was ever confused by the behaviour.
    - DrJokepu 13y ago
      Right, if this gets in then I officially demand that the much more innocent ternary operator and prefix/postfix increment/decrement operators get in as well.
      - LanceH 13y ago
        If I had to choose, I'd pick string interpolation. i += 1 means an extra line, but that extra line is very clear. Ternary vs an if-else arguably loses on clarity except for the simplest of cases. "Today's date is #{date}. Your balance on account #{account.Number} is #{account.Balance}" "Today's date is " + date + " Your balance on account " + account.Number + " is " + account.Balance The second is a mess of +'s and "'s to me, not to mention the awkwardness of formatting spaces before and after each quote. The first, you write a sentence and plug in the variables where they belong. Not saying you're wrong, just what I would choose.
  - ajanuary 13y ago
    I'm not really familiar with Go, but surely the answer to almost all of those can be "the same as variables in the same scope as the string"?
  - jongraehl 13y ago
    It would be defined as sugar for the regular syntax "blah" + var. Not sure what specifically you find confusing.
  - laumars 13y ago
    I can understand if you don't like the syntax of string interpolation, but that argument is a cop-out. If you're genuinely confused by it's behaviour then I'd suggest steering clear of the Printf (and even the vanilla Print/Println functions which does concatenation and automatic type conversion). Or perhaps, a better suggestion would be to read the language specs and learn interpolation's behaviour since this "magic" is almost always well documented [hint: it's actually less complicated than Printf ;)]
ahuth 13y ago
There isn't much difference between this: "My name is #{name} and surname is #{surname}" and this: "My name is " + name + " and surname is " + surname or this: fmt.Println("My name is %s and surname is %s", name, surname) Except the first one is much more readable. String interpolation seems like a small thing, but I find myself wanting to use it all the time. It's definitely not a "magic" feature. Javascript really needs it as well.
- lazyjones 13y ago
  > Except the first one is much more readable. I disagree, especially in the presence of syntax highlighting editors. String interpolation would be a redundant alternative to existing mechanisms (the above plus text/template for longer strings) and just make parsing more complex. I don't think it would fit in well with Go's philosophy of providing pleasant, minimalistic syntax.
  - ahuth 13y ago
    You're probably right. Also, I obviously should've said, "Except the first one is much more readable to me." I definitely don't have a problem with the Go developers keeping out random syntax additions unless they think its a really good idea. Along the same lines, I really miss not having `map`, `reduce`, and `filter` in Go. However, it doesn't seem like those would be efficient in Go, or that they fit in with as well with systems programming, which Go was designed for. So I can't hate them for not including these.
    - NateDad 13y ago
      For what it's worth, I do think it's more readable, but it's just not a good idea. It's too easy for people to inject variables into their strings and get your code to print out data that's in memory. map, reduce, filter, etc will be easy to code up once there are generics. There will almost certainly be generics in Go at some point, that point is just not right now (and almost certainly not before 2.0).
      - 13y ago
coldtea 13y ago
There's nothing "magical" about it. The intention of the programmer and the result is actually even more explicit than passing the values as arguments to some printf function.
- NateDad 13y ago
  Uh, grabbing variables out of the current scope to format your string is most certainly magical. It's also way less explicit than actually passing variables into a formatting function. It might be a little harder to read, but that's a lot different than explicit. fmt.Sprintf("Hello %s!", username) is very explicitly using the username variable from the local scope, and nothing but the username variable can ever get included in the output string. At most, a user could put a %s in their string, and get the username to appear somewhere else in the output... but they wouldn't be revealing data that wasn't already intended to be printed out. In comparison, interpolation is opening a door to let anyone extract whatever variables happen to be in scope at the time by putting #{password} or #{secret_key} in their string. By moving the definition of what variables get printed out into the data, you're opening a really big hole in your code... it also makes it a lot harder for the compiler to check for correctness.
  - ajanuary 13y ago
    Can you give an example of your last point? A language like Ruby will only perform interpolation on string literals, so there isn't a way (that I know of) for data to inject interpolated strings. Interpolation isn't the same thing as eval.
    - NateDad 13y ago
      I guess that's my lack of knowledge of how Ruby's string interpolation works. I assumed it worked like any old string format, which in other languages can use whatever string is passed into the formatting function. It sounds like that's not the case for Ruby's string interpolation. My apologies for jumping to conclusions. I guess it's my statically compiled mindset that assumes a string is a string.

thescrewdriver 13y ago

Go is designed to be a very practical and productive language. It's not quite clear how you're defining "magic" ... String interpolation is both practical and useful.

DrJokepu 13y ago
String interpolation is magic because it's not entirely obvious when it happens, what scope rules are followed, if there are any side effects, if the original string is overwritten or whether a new instance is created, what happens when they are used within bodies of loops, what happens when they are used within closures etc., it just works. Sure these can be specified explicitly but they aren't obvious. It's the kind of feature that is useful when you write an application but not that useful when you're trying to debug it.
- thescrewdriver 13y ago
  > It's the kind of feature that is useful when you write an application but not that useful when you're trying to debug it. It's largely used in log messages and the like where it's used for debugging issues after the fact. I've yet to encounter a case where anyone was ever confused by the behaviour.
  - DrJokepu 13y ago
    Right, if this gets in then I officially demand that the much more innocent ternary operator and prefix/postfix increment/decrement operators get in as well.
    - LanceH 13y ago
      If I had to choose, I'd pick string interpolation. i += 1 means an extra line, but that extra line is very clear. Ternary vs an if-else arguably loses on clarity except for the simplest of cases. "Today's date is #{date}. Your balance on account #{account.Number} is #{account.Balance}" "Today's date is " + date + " Your balance on account " + account.Number + " is " + account.Balance The second is a mess of +'s and "'s to me, not to mention the awkwardness of formatting spaces before and after each quote. The first, you write a sentence and plug in the variables where they belong. Not saying you're wrong, just what I would choose.
- ajanuary 13y ago
  I'm not really familiar with Go, but surely the answer to almost all of those can be "the same as variables in the same scope as the string"?
- jongraehl 13y ago
  It would be defined as sugar for the regular syntax "blah" + var. Not sure what specifically you find confusing.
- laumars 13y ago
  I can understand if you don't like the syntax of string interpolation, but that argument is a cop-out. If you're genuinely confused by it's behaviour then I'd suggest steering clear of the Printf (and even the vanilla Print/Println functions which does concatenation and automatic type conversion). Or perhaps, a better suggestion would be to read the language specs and learn interpolation's behaviour since this "magic" is almost always well documented [hint: it's actually less complicated than Printf ;)]

ahuth 13y ago

There isn't much difference between this: "My name is #{name} and surname is #{surname}" and this: "My name is " + name + " and surname is " + surname or this: fmt.Println("My name is %s and surname is %s", name, surname) Except the first one is much more readable. String interpolation seems like a small thing, but I find myself wanting to use it all the time. It's definitely not a "magic" feature. Javascript really needs it as well.

lazyjones 13y ago
> Except the first one is much more readable. I disagree, especially in the presence of syntax highlighting editors. String interpolation would be a redundant alternative to existing mechanisms (the above plus text/template for longer strings) and just make parsing more complex. I don't think it would fit in well with Go's philosophy of providing pleasant, minimalistic syntax.
- ahuth 13y ago
  You're probably right. Also, I obviously should've said, "Except the first one is much more readable to me." I definitely don't have a problem with the Go developers keeping out random syntax additions unless they think its a really good idea. Along the same lines, I really miss not having `map`, `reduce`, and `filter` in Go. However, it doesn't seem like those would be efficient in Go, or that they fit in with as well with systems programming, which Go was designed for. So I can't hate them for not including these.
  - NateDad 13y ago
    For what it's worth, I do think it's more readable, but it's just not a good idea. It's too easy for people to inject variables into their strings and get your code to print out data that's in memory. map, reduce, filter, etc will be easy to code up once there are generics. There will almost certainly be generics in Go at some point, that point is just not right now (and almost certainly not before 2.0).
    - 13y ago

coldtea 13y ago

There's nothing "magical" about it. The intention of the programmer and the result is actually even more explicit than passing the values as arguments to some printf function.

NateDad 13y ago
Uh, grabbing variables out of the current scope to format your string is most certainly magical. It's also way less explicit than actually passing variables into a formatting function. It might be a little harder to read, but that's a lot different than explicit. fmt.Sprintf("Hello %s!", username) is very explicitly using the username variable from the local scope, and nothing but the username variable can ever get included in the output string. At most, a user could put a %s in their string, and get the username to appear somewhere else in the output... but they wouldn't be revealing data that wasn't already intended to be printed out. In comparison, interpolation is opening a door to let anyone extract whatever variables happen to be in scope at the time by putting #{password} or #{secret_key} in their string. By moving the definition of what variables get printed out into the data, you're opening a really big hole in your code... it also makes it a lot harder for the compiler to check for correctness.
- ajanuary 13y ago
  Can you give an example of your last point? A language like Ruby will only perform interpolation on string literals, so there isn't a way (that I know of) for data to inject interpolated strings. Interpolation isn't the same thing as eval.
  - NateDad 13y ago
    I guess that's my lack of knowledge of how Ruby's string interpolation works. I assumed it worked like any old string format, which in other languages can use whatever string is passed into the formatting function. It sounds like that's not the case for Ruby's string interpolation. My apologies for jumping to conclusions. I guess it's my statically compiled mindset that assumes a string is a string.