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digitalmars.D.learn - How to use dguihub package ?

reply Vinod K Chandran <kcvinu82 gmail.com> writes:
Hi all,
I would like to use a gui package called "dguihub". So i did 
these steps.
1. Downloaded source files from Github.
2. Extract it and copy dguihub folder to my project folder. this 
folder contains all the source files of this package.
3. Write an import statement in my app.d "import dguihub;"
4. Copy paste the code from "hello" in example folder
5. Compiled with "rdmd app.d"
And i got this result.

  dguihub\toolbar.d(103): Deprecation: integral promotion not done 
for ~TBSTATE_ENABLED, use '-preview=intpromote' switch or 
~cast(int)(TBSTATE_ENABLED)

dguihub\core\menu\abstractmenu.d(187): Deprecation: variable mi 
is shadowing variable 
dguihub.core.menu.abstractmenu.RootMenu.create.mi. Rename the 
foreach variable.

dguihub\core\menu\abstractmenu.d(209): Deprecation: integral 
promotion not done for ~enabled, use '-preview=intpromote' switch 
or ~cast(int)(enabled)
dguihub\core\utils.d(130): Error: template instance to!wstring 
template to is not defined

Do i miss something ?
Jan 17 2021
parent reply Mike Parker <aldacron gmail.com> writes:
On Sunday, 17 January 2021 at 13:04:33 UTC, Vinod K Chandran 
wrote:


 Do i miss something ?


Three of those messages include the solution to fix the errors. 
The fourth one is a missing import (`import std.conv : to`) in 
dguihub.core.utils. You could fix these yourself and submit a 
pull request to the project, or submit an issue.
Jan 17 2021
parent reply Vinod K Chandran <kcvinu82 gmail.com> writes:
On Sunday, 17 January 2021 at 14:00:48 UTC, Mike Parker wrote:

 On Sunday, 17 January 2021 at 13:04:33 UTC, Vinod K Chandran
 

 Three of those messages include the solution to fix the errors. 
 The fourth one is a missing import (`import std.conv : to`) in 
 dguihub.core.utils. You could fix these yourself and submit a 
 pull request to the project, or submit an issue.


Hi Mike Parker, I just comment out the first area and write an 
import statement as you said. But I omited the ": to" part. And 
Suddenly it worked. But I think I should need to work on the 
commented code because it's the "Enabled" property of toolbar 
class. But for me, this code looks Chinese. Anyhow, I am planning 
to study this from beginning.
"b ? (tbinfo.fsState |= TBSTATE_ENABLED) : (tbinfo.fsState &= 
~TBSTATE_ENABLED);"
This is the problem line in that property. "b" is a boolean 
parameter. But I dont know what this "|="sign means in D.
Jan 19 2021
parent reply Paul Backus <snarwin gmail.com> writes:
On Tuesday, 19 January 2021 at 16:22:35 UTC, Vinod K Chandran 
wrote:

 Anyhow, I am planning to study this from beginning.
 "b ? (tbinfo.fsState |= TBSTATE_ENABLED) : (tbinfo.fsState &= 
 ~TBSTATE_ENABLED);"
 This is the problem line in that property. "b" is a boolean 
 parameter. But I dont know what this "|="sign means in D.


`a |= b` is shorthand for `a = a | b`. Similarly, `a &= b` is 
shorthand for `a = a & b`. The `|` symbol is the "bitwise or" 
operator, the `&` symbol is the "bitwise and" operator, and the 
`~` symbols is the "bitwise not" operator. [1]

The way they're being used here is to implement a bit field 
[2]--a data structure in which each bit of an integer is treated 
as a boolean "flag", where 1 is true and 0 is false. In this 
usage, the expression

     field |= FLAG

...means "take all of the bits that are set to 1 in FLAG and set 
them to 1 in field"; or, in other words, "set FLAG to true in 
field." And the expression

     field &= ~FLAG

...means "take all of the bits that are set to 0 in FLAG and set 
them to 1 in field"; or, in other words, "set FLAG to false in 
field".

You may want to take a minute with pen and paper to convince 
yourself that these particular bitwise operations actually do 
what I'm claiming they do, since it's not really obvious just 
from looking at them.

Armed with this knowledge, we can now understand the line of code 
you quoted in your message:

     b ? (tbinfo.fsState |= TBSTATE_ENABLED) : (tbinfo.fsState &= 
~TBSTATE_ENABLED);

This means, "if b is true, set the TBSTATE_ENABLED flag to true; 
otherwise, set it to false."

[1] 
https://en.wikipedia.org/wiki/Bitwise_operation#Bitwise_operators
[2] https://en.wikipedia.org/wiki/Bit_field
Jan 19 2021
parent reply Vinod K Chandran <kcvinu82 gmail.com> writes:
On Tuesday, 19 January 2021 at 16:52:18 UTC, Paul Backus wrote:

 On Tuesday, 19 January 2021 at 16:22:35 UTC, Vinod K Chandran 
 wrote:

     b ? (tbinfo.fsState |= TBSTATE_ENABLED) : (tbinfo.fsState 
 &= ~TBSTATE_ENABLED);

 This means, "if b is true, set the TBSTATE_ENABLED flag to 
 true; otherwise, set it to false."


Hi Paul Backus,
Thanks for the detailed reply. After reading your reply, I got 
the idea. But think there is one silly mistake in your reply. 
Forgive me if I am wrong.
Instead of
"if b is true, set the TBSTATE_ENABLED flag to true; otherwise, 
set it to false."

This is the meaning of that code.
if (b == true) {tbinfo.fsState = true ; } else {tbinfo.fsState = 
false;}

Because, TBSTATE_ENABLED is a  manifest constant and I cannot 
modify it.
What about simply writing this --
"tbinfo.fsState = b ; " This also worked.
Jan 20 2021
parent Paul Backus <snarwin gmail.com> writes:
On Wednesday, 20 January 2021 at 19:05:29 UTC, Vinod K Chandran 
wrote:

 On Tuesday, 19 January 2021 at 16:52:18 UTC, Paul Backus wrote:

 On Tuesday, 19 January 2021 at 16:22:35 UTC, Vinod K Chandran 
 wrote:

     b ? (tbinfo.fsState |= TBSTATE_ENABLED) : (tbinfo.fsState 
 &= ~TBSTATE_ENABLED);

 This means, "if b is true, set the TBSTATE_ENABLED flag to 
 true; otherwise, set it to false."


 Hi Paul Backus,
 Thanks for the detailed reply. After reading your reply, I got 
 the idea. But think there is one silly mistake in your reply. 
 Forgive me if I am wrong.
 Instead of
 "if b is true, set the TBSTATE_ENABLED flag to true; otherwise, 
 set it to false."

 This is the meaning of that code.
 if (b == true) {tbinfo.fsState = true ; } else {tbinfo.fsState 
 = false;}

 Because, TBSTATE_ENABLED is a  manifest constant and I cannot 
 modify it.
 What about simply writing this --
 "tbinfo.fsState = b ; " This also worked.


Not quite. If you print out TBSTATE_ENABLED in binary, you will 
see that it is an integer with exactly one bit set to 1, and all 
others set to 0. You can do this with the following line of code:

     writefln("%032b", TBSTATE_ENABLED);

By "the TBSTATE_ENABLED flag", I do not mean "the constant 
TBSTATE_ENABLED". What I mean is "the bit in tbinfo.fsState at 
the same position as the 1 bit in TBSTATE_ENABLED". To be 
clearer, I should have said something like "the 'enabled' flag in 
tbinfo.fsState".

If tbinfo.fsState were a struct instead of a bitfield:

     struct FsState
     {
         bool enabled;
         // other flags...
     }

...then the meaning of the code would be:

     if (b == true) {
         tbinfo.fsState.enabled = true;
     } else {
         tbinfo.fsState.enabled = false;
     }

Or more concisely:

     tbinfo.fsState.enabled = b;

Of course, in reality, tbinfo.fsState is a bitfield, not a 
struct, so we cannot access the individual flags with syntax like 
`.enabled`. Instead, we have to use bitwise operators. But 
conceptually, it's the same thing.

By contrast, in your proposed version:

     tbinfo.fsState = b;

...you are overwriting *all* of the flags at once, rather than 
just one of them. Even if this happens to work by coincidence 
(because "enabled" is the first flag), it will certainly cause 
you problems later on.
Jan 20 2021