I have several environments in my project.
When I use target target1 to build some binaries and shared libraries.
I want to use target target2 to build a binary and do everything that gets done for target1
I would like to achieve following,
Build and install program1 and library1 for command scons target1
Build and install program1, program2 and library1 for command scons target2
What is the right way achieve this?
The correct way to combine multiple targets under a symbolic name is the Alias() command. Check out the UserGuide at http://scons.org/doc/production/HTML/scons-user.html , especially Chapter 25. "Alias Targets". Note that an Alias is a target node itself, so you can combine multiple defined Aliases #1-#3 into a global Alias like:
alias1 = Alias("alias1", "target1")
alias2 = Alias("alias2", "target2")
alias3 = Alias("alias3", "target3")
Alias("all", [alias1, alias2, alias3])
, where you can also replace each "target" string with a reference to an actual file/dir node as it gets returned by a Builder...
Related
Like
make,
scons has a large number of predefined variables and rules. (Try scons | wc on an SConstruct containing env = Environment(); print(env.Dump()) to see how extended the set is.)
But suppose we aren't after the wizardry of presets but rather want to do something a lot more primitive—simulating launching a few instructions from the (bash, etc) command line?
Also suppose we're quite happy with the default Decider('MD5'). What is the translation of the one-souce-one-target:
out/turquoise.xyz: out/chartreuse.xyz
chartreuse_to_turquoise $< $#
of the two-source-one-target:
out/purple.xyz: out/lilac.xyz out/salmon.xyz
gen_purple $< $#
and of:
run_this:
python prog.py
which we would run on-demand by typing make run_this?
What does the SConstruct for these elementary constructs look like?
All the answers you're looking for are in the users guide (and manpage)
Firstly, assuming you don't want to scan the input files to add included files specified in the input files, you can use Commmand()
(See info here: https://scons.org/doc/production/HTML/scons-user.html#chap-builders-commands)
Then you'll want an alias to specify an a non file command line target
(See here:https://scons.org/doc/production/HTML/scons-user.html#chap-alias)
Putting those two together yields
env=Environment()
# one source, one target
env.Command('out/turquoise.xyz', 'out/chartreuse.xyz', 'chartreuse_to_turquoise $SOURCE $TARGET')
# Two source, one target
env.Command('out/purple.xyz',['out/lilac.xyz','out/salmon.xyz'], 'gen_purple $SOURCES $TARGET')
# And your .phony make target which is actually not great for reproducibility and determining when it should be rerun, because you do not specify any sources or targets
env.Alias('run_this','python prog.py')
Note: SCons doesn't NOT propagate your shell environment variables. So if you depend on (for example) a non system path in your PATH, you'll need to explicitly specify that in env['ENV']['PATH'] for example. For more details take a read through the users guide, manpage and FAQ.
https://scons.org/doc/production/HTML/scons-user.html
https://scons.org/doc/production/HTML/scons-man.html
https://scons.org/faq.html
And you can reach the community directly via our discord server, IRC channel, or users mailing list
I have a makefile in a directory of mine which builds scripts with certain environment variables set. What if I want to create another makefile in the same directory with different environment variables set? How should I name the two make files? Does makefile.1 and makefile.2 work? How do I call them?
You can give sensible names to the files like makefile.win and makefile.nix and use them:
make -f makefile.win
make -f makefile.nix
or have a Makefile that contains:
win:
make -f makefile.win
nix:
make -f makefile.nix
and use make win or make nix
You can name makefile whatever you want. I usually name it like somename.mk. To use it later you need to tell make what makefile you want. Use -f option for this:
make -f somename.mk
Actually you can have two set of environment variables in the same make file. for example
COMPILER = gcc
CCFLAGS1 = -g
CCFLAGS2 = -Wall
a: main.c
${COMPILER} ${CCFLAGS1} main.c
b: test.c
${COMPILER} ${CCFLAGS2} test.c
then you can just say make a or make b. Depending on what you want.
Also it is possible with -f flag to call which makefile you want to call.
You can do something like this rather than using multiple makefiles for the same purpose. You can pass the environment or set a flag to the same makefile. For eg:
ifeq ($(ENV),ENV1)
ENV_VAR = THIS
else
ENV_VAR = THAT
endif
default : test
.PHONY : test
test:
#echo $(ENV_VAR)
Then you can simply run the make command with arguments
make ENV=ENV1
I have two makefiles in the same directory. Many of the recipes have identical names and here are two solutions:
1. Prefix in make
proja_hello:
#echo "hello A"
projb_hello:
#echo "hello N"
2. Keep two separate files
Project A has makefile. Type make hello.
Project B has a separate make file called projb.mk. Type bmake hello.
This works since I've added alias bmake ='make -f projb.mk to my .bashrc. Note! This command can be called anywhere but only works where projb.mk exists.
Note! You lose autocompletion of make with the alias and typing make -f projb.mk hello is not better than typing make projb_hello.
I wish to write some Haskell that calls an executable as part of its work; and install this on a nixOS host. I don't want the executable to be in my PATH (and to rely on that would disrupt the beautiful dependency model of nix).
If this were, say, a Perl script, I would have a simple builder that looked for strings of a certain format, and replaced them with the executable names, based upon dependencies declared in the .nix file. But that seems somewhat harder with the cabal-based building common to haskell.
Is there a standard idiom for encoding the paths to executables at build time (including during development, as well as at install time) within Haskell code on nix?
For the sake of a concrete example, here is a trivial "script":
import System.Process ( readProcess )
main = do
stdout <- readProcess "hostname" [] ""
putStrLn $ "Hostname: " ++ stdout
I would like to be able to compile run this (in principle) without relying on hostname being in the PATH, but rather replacing hostname with the full /nix/store/-inetutils-/bin/hostname path, and thus also gaining the benefits of dependency management under nix.
This could possibly be managed by using a shell (or similar) script, built using a replacement scheme as defined above, that sets up an environment that the haskell executable expects; but still that would need some bootstrapping via the cabal.mkDerivation, and since I'm a lover of OptParse-Applicative's bash completion, I'm loathe to slow that down with another script to fire up every time I hit the tab key. But if that's what's needed, fair enough.
I did look through cabal.mkDerivation for some sort of pre-build step, but if it's there I'm not seeing it.
Thanks,
Assuming you're building the Haskell app in Nix, you can patch a configuration file via your Nix expression. For an example of how to do this, have a look at this small project.
The crux is that you can define a postConfigure hook like this:
pkgs.haskell.lib.overrideCabal yourProject (old: {
postConfigure = ''
substituteInPlace src/Configuration.hs --replace 'helloPrefix = Nothing' 'helloPrefix = Just "${pkgs.hello}"'
'';
})
What I do with my xmonad build in nix1 is refer to executable paths as things like ##compton##/bin/compton. Then I use a script like this to generate my default.nix file:
#!/usr/bin/env bash
set -eu
packages=($(grep '##[^#]*##' src/Main.hs | sed -e 's/.*##\(.*\)##.*/\1/' | sort -u))
extra_args=()
for p in "${packages[#]}"; do
extra_args+=(--extra-arguments "$p")
done
cabal2nix . "${extra_args[#]}" \
| head -n-1
echo " patchPhase = ''";
echo " substituteInPlace src/Main.hs \\"
for p in "${packages[#]}"; do
echo " --replace '##$p##' '\${$p}' \\"
done
echo " '';"
echo "}"
What it does is grep through src/Main.hs (could easily be changed to find all haskell files, or to some specific configuration module) and pick out all the tags surrounded by## like ##some-package-name##. It then does 2 things with them:
passes them to cabal2nix as extra arguments for the nix expression it generates
post-processes nix expression output from cabal2nix to add a patch phase, which replaces the ##some-package-name## tag in the Haskell source file with the actual path to the derivation.2
This generates a nix-expression like this:
{ mkDerivation, base, compton, networkmanagerapplet, notify-osd
, powerline, setxkbmap, stdenv, synapse, system-config-printer
, taffybar, udiskie, unix, X11, xmonad, xmonad-contrib
}:
mkDerivation {
pname = "xmonad-custom";
version = "0.0.0.0";
src = ./.;
isLibrary = false;
isExecutable = true;
executableHaskellDepends = [
base taffybar unix X11 xmonad xmonad-contrib
];
description = "My XMonad build";
license = stdenv.lib.licenses.bsd3;
patchPhase = ''
substituteInPlace src/Main.hs \
--replace '##compton##' '${compton}' \
--replace '##networkmanagerapplet##' '${networkmanagerapplet}' \
--replace '##notify-osd##' '${notify-osd}' \
--replace '##powerline##' '${powerline}' \
--replace '##setxkbmap##' '${setxkbmap}' \
--replace '##synapse##' '${synapse}' \
--replace '##system-config-printer##' '${system-config-printer}' \
--replace '##udiskie##' '${udiskie}' \
'';
}
The net result is I can just write Haskell code and a cabal package file; I don't have to worry much about maintaining the nix package file as well, only re-running my generate-nix script if my dependencies change.
In my Haskell code I just write paths to executables as if ##the-nix-package-name## was an absolute path to a folder where that package is installed, and everything magically works.
The installed xmonad binary ends up containing hardcoded references to the absolute paths to the executables I call, which is how nix likes to work (this means it automatically knows about the dependency during garbage collection, for example). And I don't have to worry about keeping the things I called in my interactive environment's PATH, or maintaining a wrapper that sets up PATH just for this executable.
1 I have it set up as a cabal project that gets built and installed into the nix store, rather than having it dynamically recompile itself from ~/.xmonad/xmonad.hs
2 Step 2 is a little meta, since I'm using a bash script to generate nix code with an embedded bash script in it
This is not indented to be the answer but if I post this in comment section it would turn out to be ugly formatted.
Also I am not sure if this hack is the right way to do the job.
I notice that if I use nix-shell I can get full path to nix store
Assume hash is always the same, AFAIK I believe it is, you can use it to hard-coded in build recipe.
$ which bash
/run/current-system/sw/bin/bash
[wizzup# ~]
$ nix-shell -p bash
[nix-shell:~]$ which bash
/nix/store/wb34dgkpmnssjkq7yj4qbjqxpnapq0lw-bash-4.4-p12/bin/bash
Lastly, I doubt if you have to to any of this if you use buildInput, it should be the same path.
This question already has answers here:
How does "make" app know default target to build if no target is specified?
(4 answers)
Closed 10 years ago.
In the case of building multiple targets in makefile, when I say 'make' it by default makes all the target. Is it possible to change the default of all to something else ?
all : target1 target2
Now , when I give the command 'make' , i only want target1 to build.
Like Carl mentions, you can just remove target2 from the line.
However if you still want all to make target1 and target2 there are some options...
You did not say which make you were using, which on these fine details it depends on the version, but I'm going to detail how it works for GNU make.
In GNU make, the first goal becomes the default. So if you have a Makefile like:
next:
#echo "next"
all:
#echo "All"
It will print:
$ make
next
You can also change the default goal:
.DEFAULT_GOAL=other
next:
#echo "next"
all:
#echo "All"
other:
#echo "other"
It will show:
$ make
other
This is with:
$ make --version
GNU Make 3.81
Sure, just delete target2 from that line.
Just add the line:
target1:
before the rule defining all. The name all is not special: it becomes the default by virtue of being the first rule listed. By adding target1: before that line, target1 becomes the default. Note that it is not standard behavior to allow multiple definitions of the rule (this is basically a fake rule whose behavior is defined later in the Makefile), but this will work with gnu make. If it doesn't work, just move the actual definition of target1 before the definition of all.
I want to inject a "Cleanup" target which depends on a number of other targets finishing before it goes off and gzip's some log files. It's important that I not gzip early as this can cause some of the tools to fail.
How can I inject a cleanup target for Scons to execute?
e.g. I have targets foo and bar. I want to inject a new custom target called 'cleanup' that depends on foo and bar and runs after they're both done, without the user having to specify
% scons foo cleanup
I want them to type:
% scons foo
but have scons execute as though the user had typed
% scons foo cleanup
I've tried creating the cleanup target and appending to sys.argv, but it seems that scons has already processed sys.argv by the time it gets to my code so it doesn't process the 'cleanup' target that I manually append to sys.argv.
you shouldn't use _Add_Targets or undocumented features, you can just add your cleanup target to BUILD_TARGETS:
from SCons.Script import BUILD_TARGETS
BUILD_TARGETS.append('cleanup')
if you use this documented list of targets instead of undocumented functions, scons won't be confused when doing its bookkeeping. This comment block can be found in SCons/Script/__init__.py:
# BUILD_TARGETS can be modified in the SConscript files. If so, we
# want to treat the modified BUILD_TARGETS list as if they specified
# targets on the command line. To do that, though, we need to know if
# BUILD_TARGETS was modified through "official" APIs or by hand. We do
# this by updating two lists in parallel, the documented BUILD_TARGETS
# list, above, and this internal _build_plus_default targets list which
# should only have "official" API changes. Then Script/Main.py can
# compare these two afterwards to figure out if the user added their
# own targets to BUILD_TARGETS.
so I guess it is intended to change BUILD_TARGETS instead of calling internal helper functions
One way is to have the gzip tool depend on the output of the log files. For example, if we have this C file, 'hello.c':
#include <stdio.h>
int main()
{
printf("hello world\n");
return 0;
}
And this SConstruct file:
#!/usr/bin/python
env = Environment()
hello = env.Program('hello', 'hello.c')
env.Default(hello)
env.Append(BUILDERS={'CreateLog':
Builder(action='$SOURCE.abspath > $TARGET', suffix='.log')})
log = env.CreateLog('hello', hello)
zipped_log = env.Zip('logs.zip', log)
env.Alias('cleanup', zipped_log)
Then running "scons cleanup" will run the needed steps in the correct order:
gcc -o hello.o -c hello.c
gcc -o hello hello.o
./hello > hello.log
zip(["logs.zip"], ["hello.log"])
This is not quite what you specified, but the only difference between this example and your requirement is that "cleanup" is the step that actually creates the zip file, so that is the step that you have to run. Its dependencies (running the program that generates the log, creating that program) are automatically calculated. You can now add the alias "foo" as follows to get the desired output:
env.Alias('foo', zipped_log)
In version 1.1.0.d20081104 of SCons, you can use the private internal SCons method:
SCons.Script._Add_Targets( [ 'MY_INJECTED_TARGET' ] )
If the user types:
% scons foo bar
The above code snippet will cause SCons to behave as though the user had typed:
% scons foo bar MY_INJECTED_TARGET