batch file - Delayed expansion and exclamation marks in strings

Question

Ok, so I'm still pretty new to batch scripting and I have this problem with my code that I'm using setlocal enabledelayedexpansion in my code for the for loop, the For loop goes through folder names in a specific directory, but the problem is that some of the names may include "!"(exclamation marks) and if that is the case they are not counted for in the "!filename!" and when the code creates a new directory it does not include the "!". Also when the xcopy tries to copy the files from the original folder, the folder is not found, because the variable "!filename!" is not the same as the original(does not have the exclamation point).

So I found that for this I need to only add "setlocal enable delayed expansion" to some parts of the code and turn it off at other, but I cant seem to find the right places.

The code:

@ECHO OFF
setlocal enabledelayedexpansion

SET Location_Folder=V:
SET Destination_folder=V:Nonimportable

SET Check_file_validation=V:Nonimportable
esult.txt

SET Excluded_folder=Nonimportable
set "lineNr=12"

For /f "tokens=*" %%O in ('dir /b /a:d "%Location_Folder%"') do (
    set filename=%%O

    call D:somefolderotherfolderatscriptname.bat !filename!
    set Validation=

    echo !filename!| FINDSTR /i /c:"%Excluded_folder%" >NUL
    IF ERRORLEVEL 1 (

        for /F "skip=12 delims=" %%a in (%Check_file_validation%) do if not defined Validation (
                set Validation=%%a
                call :valid
        )
    ) else (
        echo This folder name is excluded: !filename!
    )
)
goto Finish
:valid 

echo !Validation!| FINDSTR /c:"1" >NUL
    if ERRORLEVEL 1 (

        set Folder_path=%Location_Folder%!filename!
        set New_Folder_path=%Destination_folder%!filename!

        mkdir "!New_Folder_path!"

        echo D | xcopy /o /y /q /s /v "!Folder_path!" "!New_Folder_path!"

        rmdir /s /q "!Folder_path!"
    ) else (

        echo Folder is valid !filename!
        goto Finish
    )
:Finish
exit /b 

The Call part calls another small (~5lines) batch file that checks the sqlplus server if the "!filename!" is valid

EDIT: The whole code works fine and does what it should, unless there is a "!" in the name of some folder.

Answer 1

The problem is the parameter expansion in set filename=%%O. In %%O is still the exclamation mark, but when delayed expansion is enabled, the bangs are dropped.
The conclusion is simple, delayed expansion have to be disabled when you expand a FOR parameter.

But when you also need delayed expansion?
You simply toggle the mode.

setlocal DisableDelayedExpansion
For /f "tokens=*" %%O in ('dir /b /a:d "%Location_Folder%"') do (
    set "filename=%%O" -- Here the DelayedExpansion have to be disabled
    setlocal EnableDelayedExpansion

    call D:somefolderotherfolderatscriptname.bat filename
    set "Validation="
     ...
    endlocal
)

See also my modification of the CALL myBat.bat filename instead of CALL myBat.bat !filename!.
You shouldn't use content with CALL, better use a variable by reference and in your function take the content by

set "_filename=!%1!"

It's because CALL itself has some nasty behaviour with spaces, carets, etc