Parsing problems with \def with templates

Currently, a template can match in the middle of a control sequence name. For example

\def\x#1b#2.{\texttt{#1}}
\x\abc.

will output \a since the b matches in the middle of the \abc.

Also, the code

\def\x#1\a#2.{\texttt{[#1][#2]}}
\x abc \abc abc \a def .

will output [abc ][bc abc \a def] rather than the expected [abc \abc abc ][ def ].