For example, if I developed a c++ project and put it on GitHub as a open source project. In my project I used log4cpp as a 3rd-party library to do log stuff. Interested users would download my project and run "make" and suddenly found their machines just don't recognize log4cpp.
I need you guys to verify my original thoughts:
Unlike Java which you may simply include the 3rd-party jar file in your package, I know that C++ is kind of different: you have to let the client compile the library by themselves. It is obvious that, if I do not have the source code from the 3rd-party, I simply cannot help the client to install the libraries. Instead, I need to check if the user has already installed those required library and if not, just warn them not proceed.
If these statements were true, what tools should I consider to use to check? Also, an add-on question: if I want to produce a non-open source product, what should I do? (Since the client need my source code to compile.) If not(Especially the compile by themselves part), please give me your explanation.
Thanks!
Example makefile:
ifeq "$(shell echo '\#include <readline/readline.h>\nint main(){return 0;}' | $(CC) -x c -Wall -O -o /dev/null > /dev/null 2> /dev/null - && echo $$? )" "0"
HAS_FILE = yes
else
HAS_FILE = no
endif
all:
echo has_file=$(HAS_FILE)
I will not say that this is a recommended method, I just use it for simple checks. Autoconf may be a better option.
Related
Can GCC compile and run a source code without generating any output file (neither object nor executable), in a manner that is supported cross-platform? Especially, a solution supported by GCC directly.
I want to avoid generation of any trace file since that is a minor code in a big project. It just messes up the bin directory.
An existing question, here, provides a solution for compiling source code without generating any output file, such as:
gcc somefile.c -o /dev/null
However, this only compiles, and doesn't run.
Another similar question here provides a solution that is specific to Windows OS, not cross-platform.
A simple bash script might help:
#!/bin/bash
echo 'compile... ' $1
gcc $1 && ./a.out && rm a.out
supposed it's named once, then you can do
$ sh once any.c
to compile any.c and just run it once.
You can also make once executable with chmod +x once so you can just type
$ once any.c
Hope it helps ;)
In order to compile and run the C / C++ program and then remove the compiled file, you should add a function to delete the program after it is executed.
Here is a link to an example of a program that deletes itself.
Click Here
In your case (you want to avoid cluttering the build tree), a practically useful solution might be to have some convention about temporary executables.
For example, you could decide that every intermediate executable or file is named *.tmp or _* or *.tmpbin (for temporary binaries) and have some Makefile rules which removes them. Or you could use mktemp(1) in your Makefile to get a temporary file name. Don't forget to remove it later.
Also, most big projects have a compilation step and an installing step (often make install); and if you don't have that you probably should. You want your installing step to avoid installing the temporary binaries or files; with some naming convention this is quite simple: the first command for install phony target in your Makefile would remove these temporary binaries or files.
Also, you generally build in a file tree different of the final bin/ directory, so you could leave the temporary executables in the build tree.
As several people noticed, removing its own executable is easy on Linux (do a readlink(2) on "/proc/self/exe" (see proc(5) for details) then unlink(2) the result of readlink....) but difficult on Windows.
So practically your question is not a very important issue.... (if you use suitable build conventions). And GCC work on files (because it will run ld internally to build that executable file); however GCCJIT is hiding them. AFAIK, you won't even be able to use /dev/stdout as the executable output of gcc (but you can run gcc -x c /dev/stdin to compile C code from stdin). So GCC cannot avoid making an executable file (but you could have it temporary, or in a tmpfs file system or a FUSE one). So you need something external to your gcc command (perhaps simple an rm in some following line of your Makefile) to remove the produced executable.
You could also decide to have (dynamically loaded) plugins (e.g. use dlopen(3) on Linux). Your main program could load a plugin (with dlopen on Linux) - perhaps even after having generated dynamically its C++ code and having compiled that generated code into e.g. some shared object .so on Linux (or some DLL on Windows), as I do in MELT -, run functions in it obtained with dlsym, and unload the plugin (with dlclose on Linux) and finally remove it. You might use cross-platform frameworks like Qt or POCO to avoid dealing with OS specific plugin code.
For c gcc/g++ filname.c && ./a.out && rm a.out
For c++ g++ filename.cpp && ./a.out && rm a.out
I've written a simple c++ program on Xcode, all contained within ONE FILE called huffmanGenerator.cpp. The program reads input from a file on the user's computer, and writes output to a file saved to their computer.
The instructor has asked us to create a makefile so that our programs compile and run with g++ OR gcc in Linux; however she never showed us how to do so, and when the class asked for help, her answer was we could figure it out.
I found many links online, but they're all very confusing as this is all new to me, and most of them fail to answer even the most basic questions like what kind of file should the makefile be? Is it a .txt? Should I just save one in word?
Please help do what the instructor won't, enlighten me. Thanks!
what kind of file should the makefile be?
It should be a plaintext file called Makefile or makefile. The reason the name matters is because when you run the make command, it looks for a file with this name by default for directions on how to compile your code. You can also name it whatever you want as long as you specify the name when you run it (make -f filename).
Is it a .txt?
No, it has no extension. Extensions don't mean that much in *nix.
Should I just save one in word? (Assume you mean Microsoft Word.)
No, definitely not. Whitespace (tabs/spaces/new lines) have meaning in these files, so you should use an editor that won't add formatting to the file. Something like pico/vi/etc.
Here is an example of a makefile, that I think does what you are asking.
# You can change your compiler to gcc / g++ here.
CC=g++
# Add whatever flags you want to use here.
CFLAGS=-c -Wall
all:
$(CC) $(CFLAGS) huffmanGenerator.cpp -o huffmanGenerator
#Use something like this to run `make clean` which deletes your object files, so you can do a fresh compile.
#clean:
# rm -rf *o huffmanGenerator
As a side note, you would be served well not to blame your professor for not spelling out everything for you. When you graduate, you will often be given tasks that have no other directions than a set of requirements and a deadline. You will need to figure it out. You could have easily made this make file by visiting http://mrbook.org/tutorials/make/ (search google for 'makefile tutorial').
The makefile should be called Makefile. It is just a text file.
You need a text editor. There are many to choose from, vim, emacs, nano, pico, ..., etc.
Open a command line and run, say
$ pico Makefile
Then you would enter the contents of the Makefile
all:
g++ -o huffmanGenerator huffmanGenerator.cpp
Save and exit and run make
$ make
I'm new to compiling C/C++ with the aid of make. I downloaded an open source project and noticed that there is in the make file CXXSources and CXXObjects. I think I understand roughly what the make file is doing with them but...
I don't have any of the source files listed under CXXSources. Are these like dependences I'm supposed to know how to find? Is there any custom as to what CXXSource is versus just Source?
Added link to project: http://www.fim.uni-passau.de/en/fim/faculty/chairs/theoretische-informatik/projects.html
More specifically, the GML parser, eg. http://www.fim.uni-passau.de/fileadmin/files/lehrstuhl/brandenburg/projekte/gml/gml-parser.tar.gz
It seems to be getting stuck on the line:
gml_to_graph : $(CXXOBJECTS) gml_scanner.o gml_parser.o
$(CXX) -o gml_to_graph_demo $(CXXOBJECTS) gml_parser.o gml_scanner.o -L$(LEDADIR)/lib -lG -lL -lm
The $CXXObjects is defined by
CXXSOURCES = gml_to_graph.cc gml_to_graph_demo.cc
CXXOBJECTS = $(CXXSOURCES:.cc=.o)
So I need gml_to_graph.cc, it seems. Or maybe I'm wrong?
Usually, the variables are set before the point where you see them. This could be
(a) via the environment
(b) before including the quoted makefile
(c) in the quoted makefile, but preceding the location quoted
To see (verbosely) what GNU make takes into account, do:
make -Bn
(it will show everything that _would get executed)
Even more verbose:
make -p all
It will show you all the internal variable expansions.
If you post a link or more information, we will be able to come up with less generic (and hence possibly less confusing) answers
My job mostly consists of engineering analysis, but I find myself distributing code more and more frequently among my colleagues. A big pain is that not every user is proficient in the intricacies of compiling source code, and I cannot distribute executables.
I've been working with C++ using Boost, and the problem is that I cannot request every sysadmin of every network to install the libraries. Instead, I want to distribute a single source file (or as few as possible) so that the user can g++ source.c -o program.
So, the question is: can you pack the Boost libraries with your code, and end up with a single file? I am talking about the Boost libraries which are "headers only" or "templates only".
As an inspiration, please look at the distribution of SQlite or the Lemon Parser Generator; the author amalgamates the stuff into a single source file which is trivial to compile.
Thank you.
Edit:
A related question in SO is for Windows environment. I work in Linux.
There is a utility that comes with boost called bcp, that can scan your source and extract any boost header files that are used from the boost source. I've setup a script that does this extraction into our source tree, so that we can package the source that we need along with our code. It will also copy the boost source files for a couple of boost libraries that we use that are no header only, which are then compiled directly into our applications.
This is done once, and then anybody who uses the code doesn't even need to know that it depends on boost. Here is what we use. It will also build bjam and bcp, if they haven't been build already.
#!/bin/sh
BOOST_SRC=.../boost_1_43_0
DEST_DIR=../src/boost
TOOLSET=
if ( test `uname` = "Darwin") then
TOOLSET="--toolset=darwin"
fi
# make bcp if necessary
if ( ! test -x $BOOST_SRC/dist/bin/bcp ) then
if ( test -x $BOOST_SRC/tools/jam/*/bin.*/bjam ) then
BJAM=$BOOST_SRC/tools/jam/*/bin.*/bjam
else
echo "### Building bjam"
pushd $BOOST_SRC/tools/jam
./build_dist.sh
popd
if ( test -x $BOOST_SRC/tools/jam/*/bin.*/bjam ) then
BJAM=$BOOST_SRC/tools/jam/*/bin.*/bjam
fi
fi
echo "BJAM: $BJAM"
pushd $BOOST_SRC/tools/bcp
echo "### Building bcp"
echo "$BJAM $TOOLSET"
$BJAM $TOOLSET
if [ $? == "0" ]; then
exit 1;
fi
popd
fi
if ( ! test -x $BOOST_SRC/dist/bin/bcp) then
echo "### Couldn't find bpc"
exit 1;
fi
mkdir -p $DEST_DIR
echo "### Copying boost source"
MAKEFILEAM=$DEST_DIR/libs/Makefile.am
rm $MAKEFILEAM
# Signals
# copy source libraries
mkdir -p $DEST_DIR/libs/signals/src
cp $BOOST_SRC/libs/signals/src/* $DEST_DIR/libs/signals/src/.
echo -n "boost_sources += " >> $MAKEFILEAM
for f in `ls $DEST_DIR/libs/signals/src | fgrep .cpp`; do
echo -n "boost/libs/signals/src/$f " >> $MAKEFILEAM
done
echo >> $MAKEFILEAM
echo "### Extracting boost includes"
$BOOST_SRC/dist/bin/bcp --scan --boost=$BOOST_SRC ../src/*/*.[Ch] ../src/boost/libs/*/src/*.cpp ../src/smart_assert/smart_assert/priv/fwd/*.hpp $DEST_DIR
if [ $? != "0" ]; then
echo "### bcp failed"
rm -rf $DEST_DIR
exit 1;
fi
Have you considered just writing a build script for a build system like SCons?
You could write a python script to download boost, unpack it compile the needed files (you can even run bjam if needed) and compile your own code.
The only dependency your colleagues will need is Python and SCons.
Run the preprocessor on your code and save the output. If you started with one main.cpp with a bunch of includes in it, you will end up with one file where all of the includes have been sucked in. If you have multiple cpp files, you will have to concatinate them together and then run the preprocessor on the concatinated file, this should work as long as you don't have any duplicate global symbol names.
For a more portable method, do what sqlite does and write your own script to just combine and concatinate together the files you created+boost, and not get the system includes. See mksqlite3c.tcl in the sqlite code
http://www2.sqlite.org/src/finfo?name=tool/mksqlite3c.tcl
Why not just check in all the necessary files to SVN, and send you co-workers the URL of the repository? Then they can check out the code whenever they want to, do an 'svn up' any time they want to update to the latest version, etc.
If you're on a Debian-derived variety of Linux, well problems like this just shouldn't come up: let the packaging system and policy manual do the work. Just make it clear that the libboost-dev or whatever package is a build-dependency of your code and needs to be installed beforehand, and then /usr/include/boost should be right there where your code expects to find it. If you're using a more recent version of boost than the distro ships, it's probably worth figuring out how to package it yourself and work within the existing packaging/dependencies framework rather than reinventing another one.
I'm not familiar enough with .rpm based distros to comment on how things work there. But knowing I can easily setup exactly the build environment I need is, for me, one of the biggest advantages of Debian based development over Windows.
I have a bunch of files in different folders:
/ai/client.cpp # contains the main function
/ai/utils/geometry.h
/ai/utils/geometry.cpp
/ai/world/world.h
/ai/world/world.cpp
/ai/world/ball.h
/ai/world/ball.cpp
/ai/world/bat.h
/ai/world/bat.cpp
How do I write a makefile to compile this program? I'm using Ubuntu.
Make is a versatile tool, and there are many different subtleties to using it. However, you can keep things simple:
OBJ := ai/utils/geometry.o ai/world/world.o ai/world/ball.o ai/world/bat.o
all: ai/client
.PHONY: all # specific to GNU make, which is what Ubuntu provides
ai/client: ai/client.o $OBJ
# this rule means each .cpp file depends on its corresponding header
# and, since the .o files depend on .cpp files (a builtin make rule),
# they will be recompiled if the headers change
#
# you can also get more complex and generate dependencies automatically
# look at the -MM option for gcc, for example
%.cpp: %.h
you should check out that you have installed g++ and build-essential
here is some insight into the makefile black magic consorsium
I think that make1 is directory aware so typing mydirectory/myfile.cpp should work well
the rest is basic g++ commands but the tutorial on 1 should be enough :)
1 the program that executes makefiles
its working thank you every1 for your valuable comments
specially for the links
on the previous post i forgot to write the client.cpp file on line 6
but my mistake was that i had included one header with a mistake in the client.cpp and it could never find it.
First result in google: http://www.opussoftware.com/tutorial/TutMakefile.htm
Seems to be a pretty good tutorial. Should be pretty simple to understand, note that they talk about the GNU version of make, which is what is most commonly used. There is also the BSD version though if you use a BSD-based OS(such as OpenBSD, NetBSD, or FreeBSD.. anyone know about Mac OSX?)