Re: Question regarding the setter method/proc
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Re: Question regarding the setter method/proc
@Lando I think you misunderstood me. I like properties for the reasons you mentioned (mainly: not giving a damn). I just don't like the fact they work differently in the module the type is defined in. As for whether properties are good: it depends. Memoized properties are often a good usecase: after the first access it actually is just a simple read (although one could argue that as the very first call is expensive, it should not mimic simple access). Also, properties can be an alias --- in one of my projects I used some generic N-spaces but aliased a few first elements of any N-dimentional array by x, y, z etc. As for solution: why not use the same one as with assignments? system.`host=`(s, 34) sounds weird but hey, it IS weird to directly access a field when a setter for this field is defined!
Re: Question regarding the setter method/proc
@Udiknedormi: I see how that would make sense. There is that ambiguity that _a.host = 34_ can mean two completely different things inside the module: * call the assignment operator * call a procedure named _host=_ But Nim seems to consciously embrace ambiguity to accomplish separation of concerns: I can write _a.host_ in another module and not give a damn about whether this accesses a field or calls a proc which returns the value of a field and I like that. I don't want to know what encapsulation model the module I use has, I just want to use it. Much better than Java's getter/setter scheme. Also having to use a tweaked field name inside the module would feel bad to me. Maybe a big fat ambiguity warning instead of an error would do.
Re: Question regarding the setter method/proc
It seems to me it would be better to not allow a getter/setter to be named just like a private field. It's quite misleading.
Re: Question regarding the setter method/proc
Thanks again @Lando for confirming this. It more clear to me now. Best Regards
Re: Question regarding the setter method/proc
Correct. This is why the name of the field was changed to something other than _host_ in the updated example code.
Re: Question regarding the setter method/proc
@Lando, Many thanks for your reply, much appreciated. I was really confused. This is how I understand the concept from your reply. Please correct me if I am wrong. * if ' s.host = 34 ' is called from the _same module_, it will directly access the object variable bypassing the 's.host=' method/proc. * if ' s.host = 34 ' is called from a _different module_, 's.host=' method/proc is called as direct access to object variable is not allowed.
Re: Question regarding the setter method/proc
The example from the tutorial is a bit misleading, try the updated [version from the language manual](https://nim-lang.org/docs/manual.html#procedures-properties) instead. The _host_ field of a _Socket_ object is invisible to code from a different module, but the tutorial example code accesses it directly from **within the same module** with _s.host = 34_.
Re: Question regarding the setter method/proc
Aplologies, there was an error in my program, corrected now. My question still stands though. Thanks.
Question regarding the setter method/proc
Hello all,
A newbie here. I have been learning Nim using the online tutorials and is
thoroughly enjoying Nim . I have completed the part 1 and have advanced to Part
2 of the tutorial. Have a question regarding the setter methods discussed in
the 'Properties' section of the tutorial. Can you please help.
The code looks like this. It appears like **s.host = 34** is not calling the
setter proc. At the same time , s.`host=` 34 calls the setter proc.
Also is there a facility in Nim to mark class variables as Private/Public?
Thanks in advance.
type
Socket = ref object of RootObj
host: int # cannot be accessed from the outside of the module due to
missing star
proc `host=`(s: var Socket, value: int) {.inline.} =
## setter of host address
s.host = value
proc host(s: Socket): int {.inline.} =
## getter of host address
echo "inside the getter host method"
s.host
var s: Socket
new s
s.host = 34 # => does not call the host= proc. "inside the getter method"
string is not printed
s.`host=` 34 # => works as expected. host= proc is called.
