[Solved]how to add dependency to a lib?

[twicave]

I found when my *.lib is re-created, the main project will not auto-build.
How to add dependency to a lib file in .pro?

[tilsitt]

Hi,

Does "this":http://qt-project.org/doc/qt-4.8/qmake-environment-reference.html#libdepend help?

[twicave]

thanks a lot.But it's not the answer of my question.

what I mean is :

when project is very large. you need sepreate it into modules. the "module" is a lib.
when you modify lib's source code, qt creator cannot make the root project auto-build.
That is what I called "dependency" to a .lib.

BTW, I have tried the method you applied. It doesn't work either.

[twicave]

no one know the answer? I can not believe that.
It is a very important feature for a building system.
When I first meet this problem, I was so surprising.

Here is my solution, now:
Delete the main output file every time, when you build project.

[Chris Kawa]

Well, the first (obvious) thing is to set dependencies in Project->Dependencies section. This will assure correct build order, but will not force your app to re-link on lib changes.
To achieve this adding this to the .pro file works for me:
@
PRE_TARGETDEPS += <path and name of your lib>
@

[twicave]

thanks a lot krzysztof.
It works.

But why qmake doesn't auto add dependency to it's libs:
through "LIBS +="?
can anybody from QT explain the reason?