Redefine a built-in math command

Question

Possible Duplicate:
Can I redefine a command to contain itself?

I'm trying to redefine the \int command so that it will always do \int \!. So here's my attempt at that:

\renewcommand{\int}{\int \!}

But then I'd get this error:

\! TeX capacity exceeded, sorry [input stack size=5000].
\int ->\int

On the other hand, I looked up \show\int, which got me \intop \nolimits . So I tried to use it in a \renewcommand:

\renewcommand{\int}{\intop \nolimits . foobarbaz}
% The foobarbaz is for testing if the \renewcommand is effective

But no, I don't see foobarbaz in the output.

How do I redefine math commands?

Answer 1

Make a copy of the old command using \let, then use the copy to create the new command.

\let\oldint\int
\renewcommand\int{\oldint\!}