Internationalising BBC BASIC Applications
               =========================================

Instead of embedding English words and phrases into an application, you
should really externalise all human language components. This allows you (or
a user) to choose for themselves what human language the application
communicates with them in.

The principle is this. Instead of, for instance:

    PRINT "Exit program?"

use:

    PRINT mExit$

where mExit$ has been set earlier in an initialisation routine. For English,
this would be "Exit program?", but in, for example, German it would be
"Program Beenden?".

The easiest way to do this is to have a text file in the following
format:

    ----8<----
    Info:Info
    Quit:Quit
    Conv:Convert to
    Bas6:BASIC
    Text:Text
    ----8<----

and use the following messages routine:

    ----8<----
    REM Message translation
    REM ===================
    DEFFNMessages_Rd(Country$)
    in%=OPENIN(@dir$+"\Resources\"+Country$+"\Messages.txt"):IFin%=0:=TRUE
    REPEAT
      A$=GET$#in%:IF LEFT$(A$,1)="#":A$=""
      A%=INSTR(A$,":"):IF A% THEN
        A%=A%-1:REPEAT:A%=A%+1:UNTIL MID$(A$,A%,1)<>" "
        PROCVar_Assign("m"+LEFT$(A$,A%-1)+"$",""""+MID$(A$,A%+1)+"""")
      SAVE
    UNTIL EOF#in%:CLOSE#in%:in%=0
    =FALSE
    :
    DEFPROCVar_Assign(Var$,Val$)
    IF RIGHT$(Var$,1)="$":A%=EVAL("FNVar_S("+Var$+","+Val$+")"):ENDPROC
    ENDPROC
    :
    DEFFNVar_S(RETURN a$,b$):a$=b$:=0
    ----8<----

An an appropriate point in the program initialisation you should do:

    failed%=FNMessages_Rd(language name)

failed% will be non-FALSE if no messages file could be found. In this
case you should load a messages file that you, the programmer, have
supplied, for example:

    IF failed%:failed%=FNMessages_Rd("UK")

This will set a load of variables with the names specified in the Messages
file, prefixed with 'm'. With the above example, you would get
mQuit$="Quit", mConv$="Convert to", mBas6$="BASIC", mtext$="Text".

In the program itself you would use mQuit$ instead of "Quit", etc. Then, if
the user decided to use a German Messages file mQuit$ would contain
"Beenden", without the program having to be replaced.

In the same directory as the application you need a "Resources" directory
which will be searched for files for different languages. For example:

 MkIndex
 +---MkIndex.exe                MkIndex executable
 +---Resources
     +---UK
     |   +---Messages.txt       MkIndex messages in UK English
     +---Germany
         +---Messages.txt       MkIndex messages in German