I've recently seen a string with ~100 lines of code being send to the Evaluate statement. There is no arbitrary length limits that I know of for it, though it may become unwieldy to debug incorrect lines.
If you have something with hundreds lines of code of functions, and this is static (not needing to be generated on the fly from your program) you may be better off loading an offline file with the R
If you have something with hundreds lines of code of functions, and this is static (not needing to be generated on the fly from your program) you may be better off loading an offline file with the R
source
function, or consider writing a package.