How do you strip quotes out of an ECHO’ed string in a Windows batch file?

The call command has this functionality built in. To quote the help for call:

 Substitution of batch parameters (%n) has been enhanced.  You can
 now use the following optional syntax:

 %~1         - expands %1 removing any surrounding quotes (")

Here is a primitive example:

@echo off
setlocal
set mystring="this is some quoted text"
echo mystring=%mystring%
call :dequote %mystring%
echo ret=%ret%
endlocal
goto :eof

:dequote
setlocal
rem The tilde in the next line is the really important bit.
set thestring=%~1
endlocal&set ret=%thestring%
goto :eof

Output:

C:\>dequote
mystring="this is some quoted text"
ret=this is some quoted text

I should credit the ‘environment variable tunneling’ technique (endlocal&set ret=%thestring%) to Tim Hill, ‘Windows NT Shell Scripting’. This is the only book I have ever found that addresses batch files with any depth.