QT Creator "subdirs" project

[mindgames]

Hi all,

I've just started following along with Stanford's CS106X course through their online course material, to brush up on my (quite mediocre) C++. The course uses QT Creator, so I've installed version 4.0.2 on my OS X system.

The course material includes a QT "starter project"
(http://web.stanford.edu/class/archive/cs/cs106b/cs106b.1162/qtcreator/simple-project.zip)
that includes the "Stanford CPP" libraries. Note that this is not a pre-compiled library, rather, the source (.h and .cpp) files are present. I would like to use these libraries for various mini-projects I might be making as I follow along the course.

What I would like to know about is the most "hassle-free" way I could keep my projects together and automatically import the requisite libraries.

I noticed QT Creator allows making something called "subdir" projects. In the aforementioned starter project, the .pro file has the line

TEMPLATE = app

I tried changing this to

TEMPLATE=subdirs

and after Qt Creator re-parses the file, it allows me to right-click on the project name and chose the (previously greyed out) "New subproject" option.

Now after I create a new subproject, is there something I can do to make the include files (and corresponding sources) available to it? I understand I should be able to put things into the .pro file to tell the build system where everything is (although I haven't tried it yet), but is there a more straightforward way, by virtue of the "subproject" relationship?

[Jan-Willem]

Does this help? https://wiki.qt.io/SUBDIRS_-_handling_dependencies

[mindgames]

Not sure; I think the document you linked is for when you want to share a pre-built library.

I'm guessing my question isn't very well specified - all I wanted was a good way to create projects that allow me to #include "someheader.h" from the parent project (i.e. the Stanford CPP code) that the linker can resolve, without having to worry about relative paths or having to passing additional include/source directories to the build/linker system for every new project - or (alternatively) having to add a duplicate copy of the Stanford code I want to reuse in every project.

This might seem like a frivolous requirement, but I guess I was just hoping to minimize the "cognitive load" (i.e. learning c++ - the language - without the added burden of having to understanding the IDE or build system right away. But maybe that's just me being lazy.)

I suppose if I built the Stanford CPP sources as a static library first then I could use the ideas in the page you linked.

In any case, thanks!

[t3685]

@mindgames

You can alternatively setup a pri file with all the Stanford code. And include that pri file in each of your separate projects. This way you would not need a subdirs project.

https://wiki.qt.io/Including_.pro_Files

[mindgames]

@t3685 This seems like a more attractive option, I'll look into it.. thanks!

[SGaist]

Hi,

Do you mean move all your files to the subproject folder used to build your library ?

[mindgames]

@SGaist said in QT Creator "subdirs" project:

Hi,
Do you mean move all your files to the subproject folder used to build your library ?

Let me explain:

This is the file structure I get when I unzip the starter project (i've left out some things I feel are non-essential):

simple_project
  - simple_project.pro
  - lib
    - StanfordCPPLib
          - *.h
          - *.cpp
      - private
          - *.h
      - stacktrace
          - *.h
          - *.cpp
  - src
      - *.h
      - *.c

As per how the .pro file is configured, the student is expected to complete an assignment by writing all his code in the src folder, and he can just #include headers from StanfordCPPLib and hit "Build". However, this way allows only having one file containing main() in the src folder. What I would rather be able to do is make multiple projects relying on the same code (StanfordCPPLib), but which are otherwise independent of one another, each having its own main() function, and do it in a way that would allow me to keep all these "sister projects" together in the same hierarchy in a non-interfering way whilst making the least amount of additions to the .pro files or build system boilerplate.

Even though this is just for learning purposes and I can conceive of several (inelegant) ways of getting around the issue, I was wondering what the best way would be in this situation.

(I still have to look into @t3685's suggestion, at first glance it seems closest to what I want.)

[SGaist]

A more flexible sub-project setup:

complex_project
    - sub_project.pro
    - lib
        - lib.pro <- TEMPLATE = subdirs
        - StanfordCPPLib
              - StanfordCPPLib.pro
              - StanfordCPPLib.pri <- will be included by your applications
              - *.h
              - *.cpp
          - private
              - *.h
          - stacktrace
              - *.h
              - *.cpp
    - apps
        - apps.pro  <- TEMPLATE = subdirs
        - my_app
            - my_app.pro -> include(../../lib/StanfordCPPLib/StanfordCPPLib.pri)
            - *.h
            - *.cpp

StanfordCPPLib.pri will contain statements like ÌNCLUDEPATH and LIBS to set things up for the projects using that library. Doing so will avoid duplication in your apps .pro file.

[sujith D]

@SGaist Is there an automatic way to generate a .pri file
from .pro of an existing project?

[SGaist]

Hi,

Not my knowledge.

[Raad]

In your main pro file :

TEMPLATE = subdirs
SUBDIRS += \
        ADD YOUR SUBDIR NAME HERE

#To use ordered build:

CONFIG += ordered

In your subdir pro file:

TARGET=
    ...

QT  += 
    ...

SOURCES += \
    ...

HEADERS += \
    ...

FORMS += \
    ...

RESOURCES += \
    ...

[SGaist]

@Raad Please avoid ordered and specify the dependencies directly.

See this very good blog post.

[Raad]

@SGaist Thank you so much for pointing that out! I was not aware of this issue.

[SGaist]

@Raad A documentation update is in the works that will explain that.