Constructor params with same name as members

[H. S. Teoh via Digitalmars-d-learn]

On Thu, Oct 23, 2014 at 10:33:53AM +0530, Shriramana Sharma via Digitalmars-d-learn wrote:
> Hello. Please see the following code:
> 
> import std.stdio ;
> struct Pair {
> 	int x, y ;
> 	this (int x, int y) { x = x ; y = y ; }

Please don't write code like this.  How is the compiler supposed to know
that "x = x" is supposed to mean "this.x = x", as opposed to "x = x" or
"this.x = this.x" or "x = this.x"??!

I used to enjoy writing this kind of code by cleverly exploiting subtle
differences in symbol lookup rules, but eventually I realized that this
kind of coding style is riddled with subtle errors, because shadowing
member variables can lead to nasty mistakes (writing 'x' in your member
functions can sometimes mean this.x, sometimes a function parameter or
local variable) and makes the code unmaintainable (anybody else reading
the code may not be aware of the subtle lookup rules you're exploiting
to make the code work) and fragile (code changes like adding/removing a
local variable may inadvertently change the meaning of 'x' in another
line of code).

Generally, shadowing member variables with parameter names is a Bad
Idea(tm). Instead, my advice is to adopt a naming convention to
distinguish between them, e.g.:

	struct S {
		int x, y;
		this(int _x, int _y) {
			x = _x; // now no longer ambiguous
			y = _y;
		}
	}


T

-- 
Don't modify spaghetti code unless you can eat the consequences.