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!
Related
Dears,
How to get character's equivalent from another TextInput using PySimpleGUI?
Let me explain: Suppose I have those sets of data , set A and Set B, my query is once I write one characters in TextInput 1 from Set A I'll get automatically it's equivalent in Set B;
For example Set A : A, B, C, D, ........, Z
Set B : 1, 2, 3,4, ..........,26
So if I write ABC in TextInut A --> I'll get : 123 in TextInput B
Thanks in advance
import PySimpleGUI as sg
enter image description here
My apologies if I misunderstand your question.
First, special characters, like ☯, ∫, β, etc., are just Unicode characters. You can type them directly into your editor or use the Unicode escape codes. You might see this question for more help.
Second, it is unclear when you want to make this mapping. It is easiest if you type characters and then map at the end. If you want to do interactively that is harder. You can get each individual keyboard event; see (this answer)[https://stackoverflow.com/a/74214510/1320510] for an example. Because I know of no way of the exact position, you might be better getting the events, and writing the display to a second label. I would need to more a bit more about what you are doing.
Keep hacking! Keep notes.
Charles
Set option enable_events=True to A, map each char in values[A] by dictionary {'A':'1', ...}, then update B with the result when event A.
Demo Code
import string
import PySimpleGUI as sg
table = {char:str(i+1) for i, char in enumerate(string.ascii_uppercase)}
layout = [
[sg.Input(enable_events=True, key='-IN1-')],
[sg.Input(key='-IN2-')],
]
window = sg.Window('Main Window', layout)
while True:
event, values = window.read()
if event == sg.WIN_CLOSED:
break
elif event == '-IN1-':
text1 = values['-IN1-']
text2 = ''.join([table[char] if char in string.ascii_uppercase else char for char in text1])
window['-IN2-'].update(text2)
window.close()
For different case, like table = {'a':'apple', 'b':'banana', 'c':'orange'}
import string
import PySimpleGUI as sg
table = {'a':'apple', 'b':'banana', 'c':'orange'}
layout = [
[sg.Input(enable_events=True, key='-IN1-')],
[sg.Input(key='-IN2-')],
]
window = sg.Window('Main Window', layout)
while True:
event, values = window.read()
if event == sg.WIN_CLOSED:
break
elif event == '-IN1-':
text1 = values['-IN1-']
text2 = ''.join([table[char] if char in table else char for char in text1])
window['-IN2-'].update(text2)
window.close()
This question already has answers here:
Calculate string value in javascript, not using eval
(12 answers)
Closed 4 months ago.
When the text was '2+3+5+1', the logic was easy
Split('+') so the string is converted to an array.
loop over the array and calculate the sum.
check the code below
void main() {
const text = '2+3+5+1';
final array = text.split('+');
int res =0;
for (var i=0; i<= array.length -1; i++){
res+=int.parse(array[i]);;
}
print(array);
print(res);
}
Now this String "2+3-5+1" contains minus.
how to get the right response using split method?
I am using dart.
note: I don't want to use any library (math expression) to solve this exercice.
Use the .replace() method.
text = text.replace("-", "+-");
When you run through the loop, it will calculate (-).
You can split your string using regex text.split(/\+|\-/).
This of course will fail if any space is added to the string (not to mention *, / or even decimal values).
const text = '20+3-5+10';
const arr = text.split(/\+|\-/)
let tot = 0
for (const num of arr) {
const pos = text.indexOf(num)
if (pos === 0) {
tot = parseInt(num)
} else {
switch (text.substr(text.indexOf(num) - 1, 1)) {
case '+':
tot += parseInt(num)
break
case '-':
tot -= parseInt(num)
break
}
}
}
console.log(tot)
I see 2 maybe 3 options, definitely there are hundreds
You don't use split and you just iterate through the string and just add or subtract on the way. As an example
You have '2+3-5+1'. You iterate until the second operator (+ or -) on your case. When you find it you just do the operation that you have iterated through and then you just keep going. You can do it recursive or not, doesn't matter
"2+3-5+1" -> "5-5+1" -> "0+1" -> 1
You use split on + for instance and you get [ '2', '3-5', '1' ] then you go through them with a loop with 2 conditions like
if(isNaN(x)) res+= x since you know it's been divided with a +
if(!isNaN(x)) res+= x.split('-')[0] - x.split('-')[1]
isNaN -> is not a number
Ofc you can make it look nicer. If you have parenthesis though, none of this will work
You can also use regex like split(/[-+]/) or more complex, but you'll have to find a way to know what operation follows each digit. One easy approach would be to iterate through both arrays. One of numbers and one of operators
"2+3-5+1".split(/[-+]/) -> [ '2', '3', '5', '1' ]
"2+3-5+1".split(/[0-9]*/).filter(x => x) -> [ '+', '-', '+' ]
You could probably find better regex, but you get the idea
You can ofc use a map or a switch for multiple operators
i am new with f# , will be great if some 1 can help , nearly half a day gone solving this problem Thank you
module Certificate =
type T = {
Id: int
IsECert: bool
IsPrintCert: bool
CertifiedBy: string
Categories: Category.T list
}
let createPending now toZonedDateTime toBeCertifiedByName (job: Models.Job.T) (certificateType: Models.CertificateType.T) (pendingCertificate: Models.PendingCertificate.T) visualization (categories: Category.T list) =
let forCompletion = Models.PendingCertificate.getCertificateForCompletion pendingCertificate
{
Id = forCompletion.Id |> CertificateId.toInt
IsECert = Models.PendingCertificate.isECertificate pendingCertificate
IsPrintCert = Models.PendingCertificate.isPrintCertificate pendingCertificate
CertifiedBy = toBeCertifiedByName
Categories = categories}
i am getting an error in "Incomplete structured construct at or before this point"
Your formatting is all off. I will assume here that this is just a result of posting to StackOverflow, and your actual code is well indented.
The error comes from the definition of createPending: this function does not have a result. All its body consists of defining a forCompletion value, but there is nothing after it. Here's a simpler example that has the same problem:
let f x =
let y = 5
This function will produce the same error, because it also doesn't have a result. In F#, every function has to return something. The body cannot contain only definitions of helper functions or values. For example, I could fix my broken function above like this:
let f x =
let y = 5
x + y
This function first defines a helper value y, then adds it to its argument x, and returns the result.
> f 2
> 7
>
> f 0
> 5
How exactly you need to fix your function depends on what exactly you want it to mean. I can't help you here, because you haven't provided that information.
I implemented a <textarea> in Elm such that tabs indent and unindent instead of change focus to another HTML element. Works great except that unindenting sometimes causes the selection to disappear! If I'm selecting the 5th character to the 12th character, I press shift-tab, then it removes 2 tab characters, but it also makes the selection change to a cursor at position 10. The selection range should remain the same..
I have an SSCCE at Ellie: https://ellie-app.com/3x2qQdLqpHga1/2
Here are some screenshots to illustrate the problem. Pressing Setup shows this:
Then pressing Unindent should show the following (with the selection of "def\ng" still intact):
Unfortunately, pressing Unindent actually shows the following. The text is unindented fine, but the selection range goes away and there's just a cursor between the g and the h:
Interesting issue and excellent problem illustration!
The problem is that for some reason re-rendering doesn't occur when one of the selectionStart/selectionEnd properties remains the same. Try changing 5 to 6 on line #42.
It works when you introduce a forced reflow in the element structure. See here: https://ellie-app.com/6Q7h7Lm9XRya1 (I updated it to 0.19 to see if that would solve the problem, but it didn't).
Note that this probably re-renders the whole textarea anew so it might cause problems if the textarea is a huge piece of code. You could solve that by alternating between two identical textareas where you toggle their visibility every render.
module Main exposing (Model, Msg(..), main, update, view)
-- Note: this is Elm 0.19
import Browser
import Browser.Dom exposing (focus)
import Html exposing (Html, button, div, text, textarea)
import Html.Attributes exposing (attribute, class, cols, id, property, rows, style, value)
import Html.Events exposing (onClick)
import Html.Lazy exposing (lazy2)
import Json.Encode as Encode
import Task exposing (attempt)
type alias Model =
{ content : String
, selectionStart : Int
, selectionEnd : Int
-- keep counter of renderings for purposes of randomness in rendering loop
, renderCounter : Int
}
main =
Browser.element
{ init = initModel
, view = view
, update = update
, subscriptions = \s -> Sub.none
}
initModel : () -> ( Model, Cmd Msg )
initModel flags =
( Model "" 0 0 0, Cmd.batch [] )
type Msg
= Setup
| Unindent
| NoOp (Result Browser.Dom.Error ())
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
let
newRenderCounter =
model.renderCounter + 1
in
case msg of
Setup ->
( { model
| content = "\tabc\n\tdef\n\tghi"
, selectionStart = 5
, selectionEnd = 12
, renderCounter = newRenderCounter
}
, attempt NoOp <| focus "ta"
)
Unindent ->
( { model
| content = "\tabc\ndef\nghi"
, selectionStart = 5
, selectionEnd = 10
, renderCounter = newRenderCounter
}
, attempt NoOp <| focus "ta"
)
NoOp _ ->
( model, Cmd.batch [] )
view : Model -> Html Msg
view model =
div []
(viewTextarea model model.renderCounter
++ [ button [ onClick Setup ] [ text "Setup" ]
, button [ onClick Unindent ] [ text "Unindent" ]
]
)
viewTextarea : Model -> Int -> List (Html msg)
viewTextarea model counter =
let
rerenderForcer =
div [attribute "style" "display: none;"] []
ta =
textarea
[ id "ta"
, cols 40
, rows 20
, value model.content
, property "selectionStart" <| Encode.int model.selectionStart
, property "selectionEnd" <| Encode.int model.selectionEnd
]
[]
in
-- this is the clue. by alternating this every render, it seems to force Elm to render the textarea anew, fixing the issue. Probably not very performant though. For a performant version, use an identical textarea instead of the div and make sure the two selectionStart/end properties both differ from the previous iteration. Then alternate visibility between the two every iteration.
if isEven counter then
[ ta, rerenderForcer ]
else
[ rerenderForcer, ta ]
isEven : Int -> Bool
isEven i =
modBy 2 i == 0
In the following code I create 3 boxes with the text 1 to 3, in a fourth box I'd like to show the text of the box my mouse is hovering over. So i set an onMouseEnter FProperty for each of the boxes where I change the string of the fourth box and tell it to redraw.
bool redraw = false;
str s = "0";
Figure getTextbox() {
return computeFigure(bool() {bool temp = redraw; redraw = false; return temp; },
Figure() {
return text(str() {return s; });
});
}
list[Figure] boxes = [];
for (i <- [1..4]) {
boxes += box(text(toString(i)), onMouseEnter(void () {s = toString(i); redraw = true; }));
}
Figure changer = box(getTextbox());
render(vcat(boxes + changer));
However, for some odd reason all three boxes will tell the onMouseEnter method to change the text of the fourth box into "3" (the value of the last box) instead of their individual value.
Any clue why? Thanks!
Ah yes, this is the variable capturing closure problem with for loops, also known from other languages which have this particular feature like Javascript. This is the code with the issue:
for (i <- [1..4]) {
boxes += box(text(toString(i)), onMouseEnter(void () {s = toString(i); redraw = true; }));
}
The variable i is bound by the void closure and not its value. So every time the function which is created and passed to onMouseEnter it will read the latest value of the i variable. Since the callback is called after the loop terminates, all calls to the mouse enter function will have the value 3.
To fix this and "do what you want", the following code would work I believe:
for (i <- [1..4]) {
newS = toString(i);
boxes += box(text(toString(i)), onMouseEnter(void () {s = newS; redraw = true; }));
}
This works because for every pass of the for loop a new environment is created which binds the newS variable. So you'll get a fresh newS for every loop instead of the reused i.