Re: Handling CheckBox state changes in DLangUI

[torhu via Digitalmars-d-learn]

On Saturday, 31 December 2022 at 02:40:49 UTC, Daren Scot Wilson 
wrote:


The compiler errors I get are, for no '&' and with '&':

Error: function `app.checkbox_b_clicked(Widget source, bool 
checked)` is not callable using argument types `()`


Error: none of the overloads of `opAssign` are callable using 
argument types `(bool function(Widget source, bool checked))`


If checkbox_b_clicked is a non-static nested function or 
non-static method, taking the address of it should result in a 
delegate, not a function pointer.


You can check what it is like this:

writeln(typeid(&checkbox_b_clicked));

Re: Handling CheckBox state changes in DLangUI

[Daren Scot Wilson via Digitalmars-d-learn]

On Saturday, 31 December 2022 at 03:05:45 UTC, brianush1 wrote:
On Saturday, 31 December 2022 at 02:40:49 UTC, Daren Scot 
Wilson wrote:

The compiler errors I get are, for no '&' and with '&':

Error: function `app.checkbox_b_clicked(Widget source, bool 
checked)` is not callable using argument types `()`


Error: none of the overloads of `opAssign` are callable using 
argument types `(bool function(Widget source, bool checked))`


Try:

import std.functional : toDelegate;
check_c.checkChange = toDelegate(&checkbox_b_clicked);


That works :)

Re: Handling CheckBox state changes in DLangUI

[brianush1 via Digitalmars-d-learn]

On Saturday, 31 December 2022 at 02:40:49 UTC, Daren Scot Wilson 
wrote:

The compiler errors I get are, for no '&' and with '&':

Error: function `app.checkbox_b_clicked(Widget source, bool 
checked)` is not callable using argument types `()`


Error: none of the overloads of `opAssign` are callable using 
argument types `(bool function(Widget source, bool checked))`


Try:

import std.functional : toDelegate;
check_c.checkChange = toDelegate(&checkbox_b_clicked);

Handling CheckBox state changes in DLangUI

[Daren Scot Wilson via Digitalmars-d-learn]

I'm writing a GUI program using dlangui. It has some checkboxes. 
I'm trying to figure out how to invoke a callback function when 
the user clicks the box. What are the valid ways of doing that?


I can copy from dlangide's source, where a delegate is defined 
in-line and assigned. That seems to work.  But is that the only 
way?



bool g_x = true;

bool checkbox_b_clicked(Widget source, bool checked)
{
  g_x = checked;
  if (checked) {
  writeln(checked);
  }
  return true;
}


auto check_a = new CheckBox("wantalt", "Alternating"d);
auto check_b = new CheckBox("wantblinkb", "Blink(delg)"d);
auto check_c = new CheckBox("wantblinkc", 
"Blink(direct)"d);


check_a.checkChange = delegate(Widget w, bool checked) {
 g_x=checked;
 return true;
 };
check_b.checkChange = delegate(Widget w, bool checked) {
 return checkbox_b_clicked(w,checked);
 };
check_c.checkChange = checkbox_b_clicked;
check_c.checkChange = &checkbox_b_clicked;

The assignment to check_a is fine with the compiler.

For check_b, I try calling a function defined earlier. (Maybe in 
real life it's too complex to try having inline.)  It was giving 
a compiler error until I realized I'm dumb, wasn't passing 'w' 
and 'checked' to it. Fixed, works fine now. Okay!


But what I think I should be able to do: assign 
checkbox_b_clicked directly to the .checkChange property of the 
checkbox, as shown for check_c.  It doesn't work. Oh, I see an 
example where '&' is used - okay let's try that... nope!


The compiler errors I get are, for no '&' and with '&':

Error: function `app.checkbox_b_clicked(Widget source, bool 
checked)` is not callable using argument types `()`


Error: none of the overloads of `opAssign` are callable using 
argument types `(bool function(Widget source, bool checked))`