5 ms·

Method-syntax is more than syntactic sugar. It is not just about getting a function from an object and then executing that function. It is executing that func

Method-syntax is more than syntactic sugar. It is not just about getting a function from an object and then executing that function. It is executing that function in the context of the object from which you get it, by utilizing the pseudo-variable "this" (or 'self' in Smalltalk) which refers to that object from which you got that function (a.k.a "method" in this case). But definitely the ability to have editor-support for lookup of argument-types etc. is a great benefit too.

munificent 3y ago
> It is executing that function in the context of the object from which you get it, by utilizing the pseudo-variable "this" (or 'self' in Smalltalk) which refers to that object from which you got that function (a.k.a "method" in this case). Ignoring runtime polymorphism for the moment, there's nothing special about "this" or "self". It's just another function parameter. Consider how in Python it is actually explicitly declared as a parameter in the method declaration.
- masklinn 3y ago
  That is not necessarily the case though, for instance in Self (the language) `self` is the parent slot of the method activation object which contains the instance to which the message resolved. Then again there's no to functions as I don't think Self has free functions. Also lots of languages have syntactic sugar around the corresponding object e.g. implicitly dereference it for attribute access and method calls, or even give it exclusive(ish) properties like @ in Ruby (or straight up instance variable access in smalltalk). Even Python treats it specially, given a method `foo`, `obj.foo` actually returns a proxy object which partially applies `foo` to `obj`. This only works on functions defined on the class object, mere callables set on the instance don't get that treatment.
  - munificent 3y ago
    > Also lots of languages have syntactic sugar around the corresponding object e.g. implicitly dereference it for attribute access and method calls The parent comment specifically said "by utilizing the pseudo-variable 'this' (or 'self' in Smalltalk)", so I was referring to that. Yes, in languages where the receiver is implicitly added to the lexical scope chain, things get a bit more complex. > or even give it exclusive(ish) properties like @ in Ruby (or straight up instance variable access in smalltalk). Even Python treats it specially, given a method `foo`, `obj.foo` actually returns a proxy object which partially applies `foo` to `obj`. This only works on functions defined on the class object, mere callables set on the instance don't get that treatment. Sure, there's other features that object-oriented languages tend to hang off methods too, but my point was just that from the perspective of within a method body, the receiver's mostly just another parameter. This is made explicit in some languages: https://en.wikipedia.org/wiki/Uniform_Function_Call_Syntax https://en.wikipedia.org/wiki/Uniform_Function_Call_Syntax
- mathisfun123 3y ago
  In python you get more than just a self - you get easier access to the inheritance hierarchy - super() is actually a compiler supported language feature (the compiler secretly inserts the parent class intro the parens).
- galaxyLogic 3y ago
  > there's nothing special about "this" or "self" It is special in that when a method executes say in JavaScript, the 'this' has a very specific value even though you did not pass in an argument of that name nor did you ever assign a value to a local variable of that name. Depending on the language you use trying to assign to the (pseudo-) variable 'this' may or may not cause an error. The "automatic" value 'this' has makes it special, different from other variables and arguments. That automatic value ties the method-call-syntax into the semantics of what it means to call a method as opposed to calling a free function. This can be exemplified in JavaScript easily: let funk = myOb.funk; let v = myOb.funk(); let v2 = funk(); // throws error In this case the error gets thrown if myOb.funk internally refers to 'this' and tries to access some field of it. That causes an error because 'this' is undefined inside 'funk' when it is called as a plain function. When you call myOb.funk() there is NO error in the same case, because 'this' is then NOT undefined, its value is 'myOb'. You can access any field of myOb inside the code of myOb.funk when you call it as myOb.funk(). That is a big semantic difference, not just "syntactic sugar".
  - munificent 3y ago
    > the 'this' has a very specific value even though you did not pass in an argument of that name nor did you ever assign a value to a local variable of that name. It's just an implicit parameter named `this` whose argument happens to appear to the left of the `.` instead of after the `(`. Yes, there's a little extra work in the language to support this, but it's not particularly complex or deep semantically. (In fact `this` is particularly semantically shallow in JavaScript because as your example notes, it's not even bound when a reference to a method is taken. In most other languages, `myOb.funk` will give you a function that partially applies `this`.)
wtetzner 3y ago
> Method-syntax is more than syntactic sugar. No, method syntax is just syntax. In some languages methods are more than just syntax sugar, but there's nothing special about the syntax itself.
- galaxyLogic 3y ago
  Syntax has no meaning unless it is associated with some semantics, like it is in all programming languages.
  - wtetzner 3y ago
    The point is that the semantics could very well be just an alternative form of function calls.
    - galaxyLogic 3y ago
      It could be, but it is not. In JavaScript you can say: let v = myOb.myFunk(); or you can say: let v2 = myFunk.call (myOb); Those the two different syntaxes you can use to make a method-call. They have the same result for all arguments. So you can say one is syntactic sugar over the other. Their semantics are the same. In other words they have the exactly same meaning. BUT if you write: let v3 = myFunk(); the result is different. And you get an error if your source-code assumes that 'this' is not undefined. That shows that the semantics of the 3rd example above is different from the semantics of the first two. In other words the semantics of a function-call and of a method-call are different. Therefore, we can say that method-call is not syntactic sugar for doing the same thing as a plain function-call.
      - wtetzner 3y ago
        Except we were never talking about JavaScript. I thought the OP made it pretty clear that they only cared about the syntax of method calls because they flow nicely and more easily support auto-complete in editors. Simple syntax sugar that translates `foo.bar(x, y)` into `bar(foo, x, y)` would suffice for both.

munificent 3y ago

> It is executing that function in the context of the object from which you get it, by utilizing the pseudo-variable "this" (or 'self' in Smalltalk) which refers to that object from which you got that function (a.k.a "method" in this case). Ignoring runtime polymorphism for the moment, there's nothing special about "this" or "self". It's just another function parameter. Consider how in Python it is actually explicitly declared as a parameter in the method declaration.

masklinn 3y ago
That is not necessarily the case though, for instance in Self (the language) `self` is the parent slot of the method activation object which contains the instance to which the message resolved. Then again there's no to functions as I don't think Self has free functions. Also lots of languages have syntactic sugar around the corresponding object e.g. implicitly dereference it for attribute access and method calls, or even give it exclusive(ish) properties like @ in Ruby (or straight up instance variable access in smalltalk). Even Python treats it specially, given a method `foo`, `obj.foo` actually returns a proxy object which partially applies `foo` to `obj`. This only works on functions defined on the class object, mere callables set on the instance don't get that treatment.
- munificent 3y ago
  > Also lots of languages have syntactic sugar around the corresponding object e.g. implicitly dereference it for attribute access and method calls The parent comment specifically said "by utilizing the pseudo-variable 'this' (or 'self' in Smalltalk)", so I was referring to that. Yes, in languages where the receiver is implicitly added to the lexical scope chain, things get a bit more complex. > or even give it exclusive(ish) properties like @ in Ruby (or straight up instance variable access in smalltalk). Even Python treats it specially, given a method `foo`, `obj.foo` actually returns a proxy object which partially applies `foo` to `obj`. This only works on functions defined on the class object, mere callables set on the instance don't get that treatment. Sure, there's other features that object-oriented languages tend to hang off methods too, but my point was just that from the perspective of within a method body, the receiver's mostly just another parameter. This is made explicit in some languages: https://en.wikipedia.org/wiki/Uniform_Function_Call_Syntax https://en.wikipedia.org/wiki/Uniform_Function_Call_Syntax
mathisfun123 3y ago
In python you get more than just a self - you get easier access to the inheritance hierarchy - super() is actually a compiler supported language feature (the compiler secretly inserts the parent class intro the parens).
galaxyLogic 3y ago
> there's nothing special about "this" or "self" It is special in that when a method executes say in JavaScript, the 'this' has a very specific value even though you did not pass in an argument of that name nor did you ever assign a value to a local variable of that name. Depending on the language you use trying to assign to the (pseudo-) variable 'this' may or may not cause an error. The "automatic" value 'this' has makes it special, different from other variables and arguments. That automatic value ties the method-call-syntax into the semantics of what it means to call a method as opposed to calling a free function. This can be exemplified in JavaScript easily: let funk = myOb.funk; let v = myOb.funk(); let v2 = funk(); // throws error In this case the error gets thrown if myOb.funk internally refers to 'this' and tries to access some field of it. That causes an error because 'this' is undefined inside 'funk' when it is called as a plain function. When you call myOb.funk() there is NO error in the same case, because 'this' is then NOT undefined, its value is 'myOb'. You can access any field of myOb inside the code of myOb.funk when you call it as myOb.funk(). That is a big semantic difference, not just "syntactic sugar".
- munificent 3y ago
  > the 'this' has a very specific value even though you did not pass in an argument of that name nor did you ever assign a value to a local variable of that name. It's just an implicit parameter named `this` whose argument happens to appear to the left of the `.` instead of after the `(`. Yes, there's a little extra work in the language to support this, but it's not particularly complex or deep semantically. (In fact `this` is particularly semantically shallow in JavaScript because as your example notes, it's not even bound when a reference to a method is taken. In most other languages, `myOb.funk` will give you a function that partially applies `this`.)

wtetzner 3y ago

> Method-syntax is more than syntactic sugar. No, method syntax is just syntax. In some languages methods are more than just syntax sugar, but there's nothing special about the syntax itself.

galaxyLogic 3y ago
Syntax has no meaning unless it is associated with some semantics, like it is in all programming languages.
- wtetzner 3y ago
  The point is that the semantics could very well be just an alternative form of function calls.
  - galaxyLogic 3y ago
    It could be, but it is not. In JavaScript you can say: let v = myOb.myFunk(); or you can say: let v2 = myFunk.call (myOb); Those the two different syntaxes you can use to make a method-call. They have the same result for all arguments. So you can say one is syntactic sugar over the other. Their semantics are the same. In other words they have the exactly same meaning. BUT if you write: let v3 = myFunk(); the result is different. And you get an error if your source-code assumes that 'this' is not undefined. That shows that the semantics of the 3rd example above is different from the semantics of the first two. In other words the semantics of a function-call and of a method-call are different. Therefore, we can say that method-call is not syntactic sugar for doing the same thing as a plain function-call.
    - wtetzner 3y ago
      Except we were never talking about JavaScript. I thought the OP made it pretty clear that they only cared about the syntax of method calls because they flow nicely and more easily support auto-complete in editors. Simple syntax sugar that translates `foo.bar(x, y)` into `bar(foo, x, y)` would suffice for both.