\documentclass{article}
\def\foo#1{\textbf{#1}}
\def\bar#1#{\textbf{#1}}
\def\baz#{\textit{a b c} }
\begin{document}
Normal macro: \foo a b c {done}

Funky macro: \bar a b c {done}

Funkier macro: \baz {done}

\end{document}
