I am trying to work out how to populate Foo from FooConfig:
class Bar
{
int A;
int B;
}
class Foo
{
Bar BarValues;
Bar BarErrorValues;
}
class FooConfig
{
int A;
int B;
int AError;
int BError;
}
FooConfig is essentially a flattened version of Foo.
I can populate the BarValues easily with AutoMapper (by having a map defined for FooConfig to Bar), but I am having trouble getting the BarErrorValues populated - everything I try it ends up with the A and B values in it instead of the AError and BError values.
I suspect I need to use a "transformer" or RecognizePostfixes (although this does not seem to work as I tried it).
This should work "out of the box":
Mapper.CreateMap<FooConfig, Foo>()
.ForMember(d => d.BarValues, o => o.MapFrom(s => new Bar { A = s.A, B = s.B }))
.ForMember(d => d.BarErrorValues, o => o.MapFrom(s => new Bar {A = s.AError, B = s.BError}));
I think I have found the problem. It appears that if AutoMapper finds an exact match then the name transformer is never used. Bugger :( Here is the AutoMapper source code that shows it:
private static MemberInfo FindTypeMember(IEnumerable<MemberInfo> modelProperties, IEnumerable<MethodInfo> getMethods, string nameToSearch, IMappingOptions mappingOptions)
{
MemberInfo pi = modelProperties.FirstOrDefault(prop => NameMatches(prop.Name, nameToSearch));
if (pi != null)
return pi;
...
pi = modelProperties.FirstOrDefault(prop => NameMatches(mappingOptions.SourceMemberNameTransformer(prop.Name), nameToSearch));
if (pi != null)
return pi;
Related
I've got this section of code:
class Main {
static inline function difference(a:Int, b:Int, ?f:(Int, Int) -> Int):Int {
if (f == null) {
f = (a, b) -> a - b;
}
return f(a, b);
}
static function main() {
trace(difference(42, 37));
trace(difference(42, 37, (a, b) -> a - b));
}
}
Which, when I compile using haxe --main Main, fails with this error:
Main.hx:11: characters 15-50 : Cannot modify a closure parameter inside inline method
Main.hx:11: characters 15-50 : For function argument 'v'
If I change Main.difference to not be inline, this error doesn't come up and everything compiles fine.
Why does this error occur?
Edit: I've found out I can also assign the argument to a variable first, and then pass the variable to Main.difference, like this:
static function main() {
var f = (a, b) -> a - b;
trace(difference(42, 37, f));
}
Which works fine with Main.difference being inlined. How does assigning the function to a variable first change things though?
This is related to how inline functions are unwrapped by the compiler. Let us take a simpler variant of your code:
class HelloWorld {
static inline function difference(a:Int, b:Int, ?f:(Int, Int) -> Int):Int {
return f(a, b);
}
static function main() {
trace(difference(42, 37, (a, b) -> a - b));
}
}
When disabling optimizations, this will yield the following JavaScript:
HelloWorld.main = function() {
console.log("HelloWorld.hx:14:",(function(a,b) {
return a - b;
})(42,37));
};
So the body of difference has been incorporated into main using a JavaScript closure. My best guess for what is happnening in your exact case is something like this:
HelloWorld.main = function() {
var v = function(a,b) {
return a - b;
}
console.log("HelloWorld.hx:14:", (function(a,b) {
if (v == null) {
v = function(a, b) {
return a - b;
}
}
return v(a, b);
})(42, 37));
};
This alters the value of v, which exists outside of difference, which has been automatically placed there as a binding for the anonymous lambda. This is what the compiler is trying to avoid. This would not be the end of the world in your case, but in general this is bad and would lead to issues in many programs.
There is a way to inline this code perfectly by hand without this, but I think that there is some weirdness surrounding how annonymous lambdas are currently handled. The situation may improve in the future.
When you explicitly defined f in main, the compiler is intelligent enough to rename the nested f as f1, which is why the issue does not occur:
HelloWorld.main = function() {
var f = function(a,b) {
return a - b;
};
var f1 = f;
if(f1 == null) {
f1 = function(a,b) {
return a - b;
};
}
console.log("HelloWorld.hx:14:",f1(42,37));
};
But this would also work if the inline part of this function is important to you:
class HelloWorld {
static inline function difference(a:Int, b:Int, ?f:(Int, Int) -> Int):Int {
var h = f;
if (h == null) {
h = (a, b) -> a - b;
}
return h(a, b);
}
static function main() {
trace(difference(42, 37, (a, b) -> a - b));
}
}
I'm trying to multiply some string a by some integer b such that a * b = a + a + a... (b times). I've tried doing it the same way I would in python:
class Test {
static function main() {
var a = "Text";
var b = 4;
trace(a * b); //Assumed Output: TextTextTextText
}
}
But this raises:
Build failure Test.hx:6: characters 14-15 : String should be Int
There doesn't seem to be any information in the Haxe Programming Cookbook or the API Documentation about multiplying strings, so I'm wondering if I've mistyped something or if I should use:
class Test {
static function main() {
var a = "Text";
var b = 4;
var c = "";
for (i in 0...b) {
c = c + a;
}
trace(c); // Outputs "TextTextTextText"
}
}
Not very short, but array comprehension might help in some situations :
class Test {
static function main() {
var a = "Text";
var b = 4;
trace( [for (i in 0...b) a].join("") );
//Output: TextTextTextText
}
}
See on try.haxe.org.
The numeric multiplication operator * requires numeric types, like integer. You have a string. If you want to multiply a string, you have to do it manually by appending a target string within the loop.
The + operator is not the numeric plus in your example, but a way to combine strings.
You can achieve what you want by operator overloading:
abstract MyAbstract(String) {
public inline function new(s:String) {
this = s;
}
#:op(A * B)
public function repeat(rhs:Int):MyAbstract {
var s:StringBuf = new StringBuf();
for (i in 0...rhs)
s.add(this);
return new MyAbstract(s.toString());
}
}
class Main {
static public function main() {
var a = new MyAbstract("foo");
trace(a * 3); // foofoofoo
}
}
To build on tokiop's answer, you could also define a times function, and then use it as a static extension.
using Test.Extensions;
class Test {
static function main() {
trace ("Text".times(4));
}
}
class Extensions {
public static function times (str:String, n:Int) {
return [for (i in 0...n) str].join("");
}
}
try.haxe.org demo here
To build on bsinky answer, you can also define a times function as static extension, but avoid the array:
using Test.Extensions;
class Test {
static function main() {
trace ("Text".times(4));
}
}
class Extensions {
public static function times (str:String, n:Int) {
var v = new StringBuf();
for (i in 0...n) v.add(str);
return v.toString();
}
}
Demo: https://try.haxe.org/#e5937
StringBuf may be optimized for different targets. For example, on JavaScript target it is compiled as if you were just using strings https://api.haxe.org/StringBuf.html
The fastest method (at least on the JavaScript target from https://try.haxe.org/#195A8) seems to be using StringTools._pad.
public static inline function stringProduct ( s : String, n : Int ) {
if ( n < 0 ) {
throw ( 1 );
}
return StringTools.lpad ( "", s, s.length * n );
}
StringTools.lpad and StringTools.rpad can't seem to decide which is more efficient. It looks like rpad might be better for larger strings and lpad might be better for smaller strings, but they switch around a bit with each rerun. haxe.format.JsonPrinter uses lpad for concatenation, but I'm not sure which to recommend.
I'd like to know if two lists share values before applying an intersection. Something like bool DoIntersect(listA, listB) would be fabulous!
This is the code I came up with:
// Person is a class with Id and Name properties
List<Person> people1;
List<Person> people2;
// Populate people1 and people2...
// My current solution (pseudocode obviously)...
if (DoIntersect(people1, people2))
{
people1 = people1.Intersect(people2)
}
else
{
/* No shared people */
throw exception;
}
// Continue with the process...
It depends on exactly what you want:
// are there any common values between a and b?
public static bool SharesAnyValueWith<T>(this IEnumerable<T> a, IEnumerable<T> b)
{
return a.Intersect(b).Any();
}
For lists that don't overlap, this will iterate through a and b each once. For lists that overlap, this will iterate all the way through a, then through b until the first overlapping element is found.
// does a contain all of b? (ignores duplicates)
public static bool ContainsAllFrom<T>(this IEnumerable<T> a, IEnumerable<T> b)
{
return !b.Except(a).Any();
}
This will iterate through a once, then will iterate through b, stopping on the first element in b not in a.
// does a contain all of b? (considers duplicates)
public static bool ContainsAllFrom<T>(this IEnumerable<T> a, IEnumerable<T> b)
{
// get the count of each distinct element in a
var counts = a.GroupBy(t => t).ToDictionary(g => g.Key, g => g.Count());
foreach (var t in b) {
int count;
// if t isn't in a or has too few occurrences return false. Otherwise, reduce
// the count by 1
if (!counts.TryGetValue(t, out count) || count == 0) { return false; }
counts[t] = count - 1;
}
return true;
}
Similarly, this will iterate through a once, then will iterate through b, stopping on the first element in b not in a.
I believe without altering the fact that you're using a List you can't get better performance.
However, if you would have 2 sorted lists to begin with (requires overhead when creating them), then you could iterate through them with complexity of O(n) in order to find out if you have shared values.
Edit:
Although original OP doesn't have 2 sorted lists, in case someone will need it, here is the implementation for checking Intersection at O(n):
public Boolean DoIntersect(SortedList<int,String> listA,SortedList<int,String> listB )
{
if (listA == null || listA.Count == 0 || listB == null || listB.Count == 0)
{
return false;
}
var keysA = listA.Keys;
var keysB = listB.Keys;
int i = 0, j = 0;
while (i < listA.Count && j < listB.Count)
{
if (keysA[i] < keysB[j])
{
i++;
}else if (keysA[i] > keysB[j])
{
j++;
}
else
{
return true;
}
}
The above approach can be used also with IEnumerable lists, given that they are sorted, with slight variation - using GetEnumerator and iterating with it.
I'm new to Moq, and having what seems to be a silly problem.
If I perform the setup based on a loop it iwll not match, but if I do the "identicatal" setup by hand I do get a match.
I am using Moq 4.0.10827, from NuGet
My interface being mocked is simple:
public interface IMyInterface
{
string GetValue(string input);
}
The test-entire program is below.
The expected output is identical for both methods, but "Foo" is not printed for Version2()
Code:
class Program
{
static void Main(string[] args)
{
Version1();
Console.WriteLine("---------");
Version2();
Console.WriteLine("---------");
Console.ReadKey();
}
private static void Version1()
{
var mock = new Mock<IMyInterface>();
mock.Setup(x => x.GetValue(It.Is<string>(s => s == "Foo"))).Returns("Foo");
mock.Setup(x => x.GetValue(It.Is<string>(s => s == "Bar"))).Returns("Bar");
IMyInterface obj = mock.Object;
Console.WriteLine(obj.GetValue("Foo"));
Console.WriteLine(obj.GetValue("Bar"));
}
private static void Version2()
{
var mock = new Mock<IMyInterface>();
string[] keys = new string[] { "Foo", "Bar" };
foreach (string key in keys)
{
mock.Setup(x => x.GetValue(It.Is<string>(s => s == key))).Returns(key);
}
IMyInterface obj = mock.Object;
Console.WriteLine(obj.GetValue("Foo")); // Does not match anything
Console.WriteLine(obj.GetValue("Bar"));
}
}
I take it I am missing something.. but what ?
Program output:
Foo
Bar
---------
Bar
---------
Edit: Output from program
Here's a more generic way, this setup alone will let you return what you get from the parameter.
mock.Setup(item => item.GetValue(It.IsAny<string>())).Returns((string input) => input);
By using It.Is<string>(s => s == "Bar") you are probably overwriting first predicate. Try to change the order or string and check it behaves that way.
If you want to check values seperetely, you can do something like this
mock.Setup(item => item.GetValue("Foo")).Returns("Foo");
mock.Setup(item => item.GetValue("Bar")).Returns("Bar");
In a loop:
foreach (string key in keys)
{
mock.Setup(x => x.GetValue(key)).Returns(key);
}
#Ufuk is correct. To clarify, this has nothing to do with Moq. It's the classic "Access to modified closure" issue (that's the warning message ReSharper gives for it).
For example:
void Main()
{
var actions = new List<Func<string, bool>>();
string[] keys = new string[] { "Foo", "Bar" };
foreach (string key in keys)
{
actions.Add(s => s == key);
}
foreach (var action in actions)
{
Console.WriteLine("Is Foo: " + action("Foo"));
Console.WriteLine("Is Bar: " + action("Bar"));
Console.WriteLine();
}
}
Results:
Is Foo: False
Is Bar: True
Is Foo: False
Is Bar: True
See Jon Skeet's answer to C# Captured Variable In Loop and Eric Lippert's Closing over the loop variable considered harmful.
I want to implement Maybe from Haskell in D, just for the hell of it.
This is what I've got so far, but it's not that great. Any ideas how to improve it?
class Maybe(a = int){ } //problem 1: works only with ints
class Just(alias a) : Maybe!(typeof(a)){ }
class Nothing : Maybe!(){ }
Maybe!int doSomething(in int k){
if(k < 10)
return new Just!3; //problem 2: can't say 'Just!k'
else
return new Nothing;
}
Haskell Maybe definition:
data Maybe a = Nothing | Just a
what if you use this
class Maybe(T){ }
class Just(T) : Maybe!(T){
T t;
this(T t){
this.t = t;
}
}
class Nothing : Maybe!(){ }
Maybe!int doSomething(in int k){
if(k < 10)
return new Just!int(3);
else
return new Nothing;
}
personally I'd use tagged union and structs though (and enforce it's a Just when getting the value)
Look at std.typecons.Nullable. It's not exactly the same as Maybe in Haskell, but it's a type which optionally holds a value of whatever type it's instantiated with. So, effectively, it's like Haskell's Maybe, though syntactically, it's a bit different. The source is here if you want to look at it.
I haven't used the Maybe library, but something like this seems to fit the bill:
import std.stdio;
struct Maybe(T)
{
private {
bool isNothing = true;
T value;
}
void opAssign(T val)
{
isNothing = false;
value = val;
}
void opAssign(Maybe!T val)
{
isNothing = val.isNothing;
value = val.value;
}
T get() #property
{
if (!isNothing)
return value;
else
throw new Exception("This is nothing!");
}
bool hasValue() #property
{
return !isNothing;
}
}
Maybe!int doSomething(in int k)
{
Maybe!int ret;
if (k < 10)
ret = 3;
return ret;
}
void main()
{
auto retVal = doSomething(5);
assert(retVal.hasValue);
writeln(retVal.get);
retVal = doSomething(15);
assert(!retVal.hasValue);
writeln(retVal.hasValue);
}
With some creative operator overloading, the Maybe struct could behave quite naturally. Additionally, I've templated the Maybe struct, so it can be used with any type.