compile library in IDE0016, but found in IDE0021

I was given a version of Arduino IDE v0016. It appears to be useful because code changed (e.g. Wire.cpp) will be automatically recompiled if the .o is deleted. But I do not find this convenience in the latest IDE v0021.

Am I missing something ? Wish someone can point me to a suitable document so that I can understand more about this in Development.

(probably, the Question can be rephrased as ... how to force library.cpp to recompile and be linked in v0021 ?)

-Frankie.

the Question can be rephrased as ... how to force library.cpp to recompile and be linked in v0021 ?

No need to. Libraries are now compiled every time the sketch is.

That’s very helpful answer.

Take Wire library as an example, if I need to make a minor modification in it. The changed Wire.cpp (by me) will be compiled ‘every time’. If header is also modified, do #include “Wire.h”. Am I correct?
thanks PaulS.
-Frankie.