I've created a custom google spreadsheet function via the script editor that calculates pace. I call the function in my spreadsheet via
=pace(00:33:00,10,km)
and the logic for the function is
function pace(time, dist, unit)
{
return pace(time.getHours(),time.getMinutes(),time.getSeconds(), dist, unit);
}
function pace(hrs,mins,secs,dist,unit)
{
var d = dist;
if(unit=="m"||unit="M")
d = dist*1.609344;
var minutes = 60*hrs+mins+secs/60.0;
var pace = minutes/d;
return pace;
}
but when the function is executed all i get is
error: Invalid assignment left-hand side.
I think the logic is correct and the issue is related to the publication status of the script?
H,
It seems you are missing and equal sign in the second argument to your if statement.
if(unit=="m"||unit=="M")
Related
I can't understand how the closure works in Dart. Why does BMW stay? This explanation causes my neurons to overheat. A lexical closure is a functional object that has access to variables from its lexical domain. Even if it is used outside of its original scope.
`void main() {
var car = makeCar('BMW');
print(makeCar);
print(car);
print(makeCar('Tesla'));
print(car('Audi'));
print(car('Nissan'));
print(car('Toyota'));
}
String Function(String) makeCar(String make) {
var ingane = '4.4';
return (model) => '$model,$ingane,$make';
}`
Console
Closure 'makeCar'
Closure 'makeCar_closure'
Closure 'makeCar_closure'
Audi,4.4,BMW
Nissan,4.4,BMW
Toyota,4.4,BMW
Calling car('Audi') is equal to calling (makeCar('BMW'))('Audi');
A lexical closure is a functional object that has access to variables from its lexical domain. Even if it is used outside of its original scope.
in simple english:
String make will stay valid as long as the returned function is not out of scope because the returned function has reference to String make.
In essence, you "inject" information needed for the newly created function. Your car knows that make is "BMW"
I think I figured it out. Here is an example where I left comments. Maybe it will help someone.
void main() {
var pr = funkOut(10); // assign a reference to an object instance
// of the Function class to the pr variable. pr is a closure because
// it is assigned a reference to an instance that contains a lexical
// environment (int a) and an anonymous function from this environment.
// 10 transfer to a
print(pr(5)); // 5 transfer to b //15
print(pr(10)); // 10 transfer to b //20
pr = funkOut(20);// 20 transfer to a
print(pr(5)); // 5 transfer to b //25
print(pr); // Closure: (int) => int
}
Function funkOut(int a) {
return (int b) => a + b;
}
I am learning Dart, and I can't understand the logic behind this code if anyone can help:
Function applyMultiplier(num multiplier) {
return (num value) {
return value * multiplier;
};
}
final triple = applyMultiplier(3);
print(triple(6)); //output 18
There is an anonymous function inside a named function.
We assigned a function to a variable.
What I don't understand is how did we pass from triple to value. I can't understand the logic behind.
Well, the function applyMultiplier takes a num as argument and returns a function that itself returns the value it is given multiplied by another multiplier. final tripple = applyMultiplier(3) stores this function that is returned from applyMultiplier in the variable triple. Because the variable triple then stores a function it can also be used like a function.
I'm trying to draw some boxes in Rascal and trying to give each box its own callback function. On entering the box with the mouse the corresponding string should get displayed in the text element (so hovering box1 should display box1 etc.).
However, at the moment the text does pop up but just displays "box3" for each of the 3 boxes.
Any ideas?
strings = ["box1", "box2", "box3"];
boxes = [ box(
size(100, 100),
onMouseEnter(void() {
output = s;
})
) | s <- strings];
render(hcat([
vcat(boxes),
text(str () {return output;})
]));
Good question, classical problem. The essence of the problem is that Rascal uses "non-capturing closures": this means that functions that are returned from another function share the same context. In your case this is the variable s introduced by s <- strings. This nearly always happens when you create function values in a loop (as you do here). The solution is to wrap another function layer around the returned function.
Here is a simple example:
list[int()] makeClosures()
= [ int() {return i;} | i <- [0,1,2]];
void wrong(){
lst = makeClosures();
println(lst[0]());
println(lst[1]());
println(lst[2]());
}
which will print surprisingly the values 2,2and2`. The solution is, as said, to introduce another function level:
int() makeClosure(int i)
= int() { return i;};
list[int()] makeClosuresOK()
= [ makeClosure(i) | i <- [0,1,2]];
void right(){
lst = makeClosuresOK();
println(lst[0]());
println(lst[1]());
println(lst[2]());
}
now calling right() will print 1, 2, and 3 as expected.
I leave it as an exercise how this is done in your example, but I am prepared to give a solution when you ask for it. Good luck!
In the Lua C API I can store a number or a string from the stack with lua_tostring().
How can a “reference” (if that is the correct term) to a Lua function be passed to C through the Lua API? So it can be called later from C, with lua_call(), without having to reference it by its name.
(It really needs to be like that, the C program will call the function somewhere in the future and the program doesn't know anything about the function because the functions to be passed are defined in the Lua program)
In C you can't refer to Lua functions directly but you can represent numbers and strings. So, for a function to "be called later", you can store this function in some table and refer to it by a numeric or string key of the table.
Here's a simpleminded mechanism to start with:
On the Lua side:
funcs = {}
local function register_hanlder(key, fn)
funcs[key] = fn
end
register_handler("on_mouse_click", function()
print "You clicked me!"
end)
On the C side:
/* code not tested */
lua_getglobal(L, "funcs");
lua_getfield(L, -1, "on_mouse_click");
if (!lua_isnil(L, -1)) {
lua_call(L, 0, 0);
else {
// nothing registered
}
Instead of registering the functions in a global table you can register them in the registry table (see luaL_ref). You'll get some integer (that's the key in the registry table where the function value is) that you can pass around in you C code.
Note that if you don't need to store a Lua function "for use later" you don't need any of this: if your C function has some Lua function passed to it via argument you can call it outright.
== Edit:
As I mentioned, instead of using a global variable (the funcs above) you can store the reference to the function in the "registry". Conceptually there's no difference between this method and the previous one.
Let's re-use the previous example: you want the Lua programmer to be able to register a function that would be fired whenever a mouse is clicked in your application.
The Lua side would look like this:
register_mouse_click_handler(function()
print "the mouse was clicked!"
end)
On the C side you define register_mouse_click_handler:
static int the_mouse_click_handler = 0;
static int register_mouse_click_handler(lua_State* L) {
the_mouse_click_handler = luaL_ref(L, LUA_REGISTRYINDEX);
return 0;
}
(...and expose it to Lua.)
Then, in your application, when the mouse is clicked and you want to call the Lua function, you do:
...
if (the_mouse_click_handler != 0) {
lua_rawgeti(L, LUA_REGISTRYINDEX, the_mouse_click_handler);
lua_call(L, 0, 0);
} else {
// No mouse handler was registered.
}
...
(I may have typos in the code.)
In JavaScript you can do this to assign a function to multiple references:
z = function(){
console.log(1)
}
x = y = z
Now when we call x or y, 1 gets printed to the console.
Is this possible in dart?
Yes, just like in JavaScript, functions are first class citizens and can be assigned to variables.
Also see this somewhat older, but still relevant video Functions are Fun, Pt2.
As Example from the video:
loudPrint(String msg) {
print(msg.toUpperCase());
}
var loudify = loudPrint;
loudify('Dart is fun');
// DART IS FUN