combine macro arguments with text

Question

I have a macro where I need to combine one of it's arguments with text to form a string that is used in lua.

\newcommand{\mymacro}[1]{\directlua{
    myfunc("#1 4")
}

if I call \mymacro{alpha} I need myfunc to receive alpha4 and not alpha 4

any ideas?

Answer 1

Your \mymacro is a standard TeX macro: it does not matter at all that it includes \directlua. As such, the standard rules for replacement of material apply. When you define \mymacro with "#1 4", you are telling it to substitute in #1, then a blank space, then a 4. So its entirely to be expected that the space appears in the output.

As was indicated in a comment, TeX only allows up to nine arguments to a macro (and indeed working with a macro with nine arguments is pretty awkward). As such, you should miss out the space here or write your definition such that you use additional lines to divide up concepts

\newcommand{\mymacro}[1]{%
  \directlua{%
    myfunc(
     "%
       #1%
       4%
     "
     )
  }%
}