StrFunc.nsh is not very conducive to use in multiple headers

To use the macros in StrFuncs.nsh, we're supposed to make a decleration that we want to use them, which in turn redefines the original macro name and prepares it for use, e.g. to use StrLoc:

!include StrFunc.nsh
${StrLoc}

Section
    Push $0
    ${StrLoc} $0 abcdefg def >
    MessageBox MB_OK "Result was $0"
    Pop $0
SectionEnd

That's fine in one .nsi or .nsh file, but if we include a second header that also does this...

!include StrFunc.nsh
${StrLoc}

... then things blow up.

!insertmacro: macro "FUNCTION_STRING_StrLoc_Call" requires 4 parameter(s), passed 0!

And we want to be able to do that so that if our headers depend on StrLoc they can be included easily in any script that might need them.

I don't know if there's an easy solution to this, since we don't have support for overloaded macros by argument count. However, it would be nice if a workaround for this design issue was available.

For example, I've currently done this:

!ifndef UnStrLoc 
${StrLoc}
!endif

This works because UnStrLoc is defined once ${StrLoc} is processed the first time. But its very non-obvious to maintainers what is going on. Maybe StrFuncs.nsh could maintain backwards-compatibility by continuing to support the old method, but provide a safer way to declare use of a mechanism that is safe to insert more than once, and just does nothing if it's being used for the nth time. E.g. perhaps I could write:

!include StrFunc.nsh
${UseStrLoc}