http://d.puremagic.com/issues/show_bug.cgi?id=3971
--- Comment #19 from [email protected] 2011-11-15 23:56:31 PST --- (In reply to comment #18) > See: > > http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=149289 This is from that post: This also means this is currently accepted: void main() { int[3] a; a = 1; assert(a == [1, 1, 1]); } While this is not accepted: void main() { int[] b = new int[3]; b = 1; assert(b == [1, 1, 1]); //Error: cannot implicitly convert expression (1) of type int to int[] } I'd like D to require a[]=1 in that first case too. I'd like the [] to be required every time an O(n) vector operation is done, for: - constancy with all other vector operations among two arrays, that require []; - and to avoid unwanted (and not easy to spot in the code) O(n) operations; - bugs and confusion in D newbies that don't have memorized all current special cases. On the other hand Don says that [] is only required for lvalues. I think this boils to a new table like this: Rhs is an array, is it compilable? a / b a=b a[]=b a=b[] a[]=b[] int[3u] / int[3u] FALSE true FALSE true int[3u] / int[] FALSE true FALSE true int[] / int[3u] FALSE true FALSE true int[] / int[] true true true true Rhs is a element, is it compilable? a a=N a[]=N a[0..2]=N int[3u] FALSE true true int[] false true true Now if there's a [] on the left, then it's an O(n) vector operation (like a copy), otherwise it's O(1). That also means: void main() { int[] a = new int[3]; int[] b = new int[3]; a = b; // OK, copies just array fat reference } void main() { int[3] a, b; a = b; // Not OK, hidden vector op } I am not sure this new table is fully correct, but it's a start. Fixes of mistakes are welcomes. ----------------------- This is an alternative proposal. On the other hand this vector op syntax doesn't currently compile: void main() { int[3] a, b; a[] += b; } So if array assign is seen as a normal vector op, then the [] is needed on the right too: Rhs is an array, is it compilable? a / b a=b a[]=b a=b[] a[]=b[] int[3u] / int[3u] FALSE FALSE FALSE true int[3u] / int[] FALSE FALSE FALSE true int[] / int[3u] FALSE FALSE FALSE true int[] / int[] true FALSE FALSE true Rhs is a element, is it compilable? a a=N a[]=N a[0..2]=N int[3u] FALSE true true int[] false true true Where the two cases with dynamic arrays are syntax errors to keep more symmetry: void main() { int[] a = new int[3]; int[] b = new int[3]; a[] = b; // error a = b[]; // error } -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
