问题
What indicator do you use for member declaration in F#? I prefer
member a.MethodName
this is to many letters and x is used otherwise.
回答1:
I do almost always use x as the name of this instance. There is no logic behind that, aside from the fact that it is shorter than other options.
The options that I've seen are:
member x.Foo // Simply use (short) 'x' everywhere
member ls.Foo // Based on type name as Benjol explains
member this.Foo // Probably comfortable for C# developers
member self.Foo // I'm not quite sure where this comes from!
member __.Foo // Double underscore to resemble 'ignore pattern'
// (patterns are not allowed here, but '__' is identifier)
The option based on the type name makes some sense (and is good when you're nesting object expressions inside a type), but I think it could be quite difficult to find reasonable two/three abbreviation for every type name.
回答2:
Don't have a system. Wonder if I should have one, and I am sure there will be a paradigm with its own book some day soon. I tend to use first letter(s) of the type name, like Benjol.
This is a degree of freedom in F# we could clearly do without. :)
回答3:
I tend to use some kind of initials which represent the type so:
type LaserSimulator =
member ls.Fire() =
回答4:
I largely tend to use self.MethodName, for the single reason that self represents the current instance by convention in the other language I use most: Python. Come to think of it, I used Delphi for some time and they have self as well instead of this.
I have been trying to convert to a x.MethodName style, similar to the two books I am learning from: Real World Functional Programming and Expert F#. So far I am not succeeding, mainly because referring to x rather than self (or this) in the body of the method still confuses me.
I guess what I am saying is that there should be a meaningful convention. Using this or self has already been standardised by other languages. And I personally don't find the three letter economy to be that useful.
回答5:
Since I work in the .NET world, I tend to use "this" on the assumption that most of the .NET people who encounter F# will understand its meaning. Of course, the other edge of that sword is that they might get the idea that "this" is the required form.
.NET self-documentation concerns aside, I think I would prefer either: "x" in general, or -- like Benjol -- some abbreviation of the class name (e.g. "st" for SuffixTrie, etc.).
回答6:
The logic I use is this: if I'm not using the instance reference inside the member definition, I use a double underscore ('__'), a la let-binding expressions. If I am referencing the instance inside the definition (which I don't do often), I tend to use 'x'.
来源：https://stackoverflow.com/questions/3912821/f-instance-syntax