How do I avoid absolute pathnames in my code when using Git? - repository

Up till this point in my programming career, I have mostly worked on small projects, editing the PHP/Perl/Python files directly on the Linux dev host, then copying the files to the same directory on a live server to push them into production.
I'm trying to set it up now by learning how to use Git and also how to properly write code with Git in mind. I want to learn the best practices for this scenario:
Here's a project called "BigFun", which also uses some libraries with tasks that are common to many projects.
/home/projects/BigFun/bin/script1.pl
/home/projects/BigFun/bin/script2.pl
/home/projects/BigFun/bin/script3.pl
/home/projects/BigFun/lib/FunMaker.pm
/home/projects/common/lib/Utilities.pm
/home/projects/common/lib/Format.pm
If this program is not managed by Git, and if I know that the files will never be moved around, I could do something like this:
#!/usr/bin/perl
use warnings;
use strict;
use lib '/home/projects/BigFun/lib';
use FunMaker;
use lib '/home/projects/common/lib';
use Utilities;
But once this is managed by Git, then anyone will be able to check these files out and put them in their own development space. The hardcoded URLs will not work anymore if your development rootdir is "C:\My Projects\BigFun".
So, some questions:
I can probably assume that the BigFun "lib" directory will always be relative to the "bin" directory. So maybe I could change line 3 to use lib '../lib'; . Is that the right solution, though?
It seems likely, though, that this example code I've listed would be split up in to two repositories - one for BigFun, and the other as a "common" repo containing some tools that are used by many projects. When that happens, it seems to me that the BigFun code would have no way of knowing where to find the "common" libraries. /home/projects/common/lib is not at all guaranteed to work, and nor would ../../common/lib. What's the normal Git way to handle something like this?
I'm working my way through the "Pro Git" book, but I haven't (yet) found anything to answer these questions. Thanks to anyone who can point me in the right direction!

Your question is not about Git,
it's about collaboration.
Absolute paths force all users of your piece of software to use the same directory layout, and that's unacceptable. No decent software does that.
Avoiding absolute paths in software is the norm,
regardless of what version control system you use, or not use.
How to make your software work using strictly relative paths and never absolute paths? That depends on the software/framework/language.
For relative paths to make sense,
you need to consider the question: relative from where?
Here are some ideas as the anchor from which relative paths could be considered:
current working directory
user home directory
package installation directory
framework installation directory
Every language typically has some packaging mechanism.
The goal of packaging is that developers in the language can create a standard package, the content of which is organized in such a way that the standard tools of the language can install it,
adding the software to the system-wide libraries of the language,
or to custom user libraries,
or to a specified library location.
Once the software is installed, from a standard package,
it becomes ready to use just like any other installed software.
In your example,
use warnings; and use strict; work without any setup because these libraries are installed in the system.
The system finds their location relative to the installation directory of Perl. Roughly speaking.
So what you need to do is:
Figure out how to package a Perl library
Figure out how to install a Perl package
Once your FunMaker and Utilities are installed as standard Perl packages, you will be able to simplify your script as:
#!/usr/bin/perl
use warnings;
use strict;
use FunMaker;
use Utilities;
You will of course have to document the dependencies of the script (FunMaker, Utilities),
as well as how to install them (especially the location where these packages will be hosted).

Related

CMake search path configuration

we working on a C++/CMake project, that needs to run in both Windows and Linux. On Windows, we have to work with a number Visual Studio versions, both in 32- and 64 bit. In order to alleviate dependency issues in our team, we have manually compiled a number of dependencies for each configuration(vs2013_x64, vs2013_x86, vs2012_x64, vs2013_x86...) and installed them (using make install or similar commands) to a common folder for each configuration. Now we have a folder called "vs2013_x64" for example, that contains similar folders as /usr would on linux: CMake, include, lib, share, ...
Now my question is: How do I have to set up CMake, so that it treats this vs2013_x64 folder just like it does /usr on Linux?
I found a number of variables that seem related, for example
CMAKE_FIND_ROOT_PATH and CMAKE_SYSROOT. However, setting them to my vs2013_x64 folder for example does not work: FindXXX.cmake files in the vs2013_x64/CMake folder are not found, and even when I manually set the CMAKE_MODULE_PATH to that CMake folder, the Find* scripts are unable to find the include they are looking for, because the vs2013_x64/include folder does not appear to be searched.
A solution that did work was to set the CMAKE_PREFIX_PATH. This is nice and almost what I need, but lets say that on Linux, I would not want it to look at /usr at all under any circumstances. This would not be possible using the PREFIX_PATH solution if I understand it correctly.
From what I understood from the documentation,
CMAKE_FIND_ROOT_PATH is more configurable and has a number of additional variables such as CMAKE_FIND_ROOT_PATH_MODE_PROGRAM, CMAKE_FIND_ROOT_PATH_MODE_LIBRARY and CMAKE_FIND_ROOT_PATH_MODE_INCLUDE. This makes me believe that FIND_ROOT_PATH is what I actually SHOULD be doing - yet I am unable to make it work
Does what I am trying to do make sense? Can anyone clarify when and how to use what? Ideally, I would like a solution that allows me to set the search path to my vs2013_x64 folder on Windows, that defaults to /usr on Linux, but can optionally also be set to another directory containing lib/include/cmake folders. In addition, it would be nice if searching ONLY occurred in the configured path and nowhere else (to avoid mistakenly picking a library that was installed system-wide).
Thanks!

Why won't OSA_LIBRARY_PATH not work as documented for JXA?

According to Apple's Developer Docs the Library global allows one to import compiled scripts so they can be used as a library in one's current script. This works just fine if you were to do something like the below code with myLibName.scpt located at ~/Library/Script Libraries:
myLib = Library('myLibName');
myLib.myLibMethod() // Works just fine
But, the docs also claim that one can export an environment variable — OSA_LIBRARY_PATH containing a string of : delimited paths — and Library() would then defer to that list of paths before proceeding to it's default path: ~/Library/Script Libraries. Ya know, like the bash environment variable Path. Here's the relevant piece of documentation below; it describes the path hierarchy:
The basic requirement for a script to be a script
library is its location: it must be a script document in a “Script
Libraries” folder in one of the following folders. When searching for
a library, the locations are searched in the order listed, and the
first matching script is used:
If the script that references the library is a bundle, the script’s
bundle Resources directory. This means that scripts may be packaged
and distributed with the libraries they use.
If the application running the script is a bundle, the application’s bundle Resources
directory. This means that script applications (“applets” and
“droplets”) may be packaged and distributed with the libraries they
use. It also enables applications that run scripts to provide
libraries for use by those scripts.
Any folders specified in the environment variable OSA_LIBRARY_PATH. This allows using a library
without installing it in one of the usual locations. The value of this
variable is a colon-separated list of paths, such as /opt/local/Script
Libraries:/usr/local/Script Libraries. Unlike the other library
locations, paths specified in OSA_LIBRARY_PATH are used exactly as-is,
without appending “Script Libraries”. Supported in OS X v10.11 and
later.
The Library folder in the user’s home directory, ~/Library.
This is the location to install libraries for use by a single user,
and is the recommended location during library development.
The
computer Library folder, /Library. Libraries located here are
available to all users of the computer.
The network Library folder,
/Network/Library. Libraries located here are available to multiple
computers on a network.
The system Library folder, /System/Library.
These are libraries provided by OS X.
Any installed application
bundle, in the application’s bundle Library directory. This allows
distributing libraries that are associated with an application, or
creating applications that exist solely to distribute libraries.
Supported in OS X v10.11 and later.
The problem is that it doesn't work. I've tried exporting the OSA_LIBRARY_PATH variable — globally via my .zshrc file — and then running a sample script just like the one above via both the Script Editor and the osascript executable. Nothing works; I get a "file not found" error. I found this thread-where-the-participants-give-up-hope online; it doesn't explain much. Any thoughts?
On a somewhat related note, the Scripting Additions suite provides two other methods — loadScript and storeScript — that seem like they might be useful here. Unfortunately, when you try to use them, osascript gives you the finger. Though, I did manage to return what looked like a hexadecimal buffer from a compiled script using loadScript. Anyway, any insight you guys can shed on this would be much appreciated. Thanks.
The OSA_LIBRARY_PATH environment variable is ignored by restricted executables when running with System Integrity Protection enabled.
To workaround this limitation you can either turn off SIP, or you can use an unrestricted executable.
For instance, to make osascript unrestricted, you should first make a copy, and then re-sign it with an ad-hoc signature:
cp /usr/bin/osascript ./osascript
codesign -f -s - ./osascript
Once you have the unrestricted osascript, you can run it with the OSA_LIBRARY_PATH environment variable set like this:
OSA_LIBRARY_PATH="/path/to/libs" ./osascript path/to/script.scpt
As a lousy alternative, you can put a symlink at one of the "Script Libraries" folders that osascript would look at and point it to the folder you want. Note that the symlink must be a replacement for the entire folder, it can't just exist inside of it.
rm -rf ~/Library/Script\ Libraries
ln -s "/Your/Custom/Path/Goes/Here/" ~/Library/Script\ Libraries
Tested on 10.13.2

Can a git repository have N working trees

I try to write a file store based on libgit2.
Software snapshots should be saved as branches mysoftware and specific versions committed and tagged. Then later I want to checkout the tags to different directories.
When looking at git_checkout_tree, it seems like there is only one working tree for a repository and thus it does not even seem possible to checkout multiple working trees concurrently.
Is this correct!?
EDIT:
Additionally, I would like for this thing to work on Windows without the need for cygwin!
The git_checkout_opts structure in libgit2 contains a target_directory option that will allow git_checkout_tree() to write to a different directory instead of using the default working tree for the repository. This would allow you to custom build a solution with libgit2 that maintained multiple checked out copies.
Without using that option, a libgit2 git_repository object expects there will be just one working directory and looks to the core.worktree config option if it isn't the "natural" working directory for the repository.
The git-new-workdir tricks with symlinks in the .git directory don't work great with libgit2 right now, I'm afraid, and particularly doesn't work well on Windows. I'd love to see this addressed, but it isn't too high on my priority list.
Git doesn't support this natively, but you can use git-new-workdir to do it.

How to prevent Arduino IDE from moving sketch into new directory?

I have a few sketches I'd like to distribute together. All of them use a custom library which resides in the same folder. The current directory structure is totally flat. All .ino files are in a single folder, right next to the .cpp and .h files for the library. This makes it easy to distribute and update.
This would work perfectly, except that each time I open one of the sketches to upload, the Arduino IDE forces me to move it into a subfolder, then it can't find the custom library. Is there any way to disable this behavior, or can anyone suggest a workaround? Thanks!
I tried at first to do all flat and found it never ending battle. Rather than always working around that, I work with it. My example.
Where I have my local repo in some arbitrary location, then have symbolic links in the ./arduino/library/. directory pointing to them appropriate directories in the repo. In the example I have symbolic links for both SdFat and SFEMP3shield in the ./library/. directory. I use windows so rather than links (or the ln -s command) I use "hard junctions".
Note the libraries use a directory structure of ./ardunio/library/foo/example/bar/bar.ino. So I actually do all my projects in the ./example/bar/bar.ino sketch. Also its worth noting that I use an external editor (like notepad++).
This way my repo can have more or less of what I specify it to.

Flash Builder 4.6 linked Resources not working with ANEs and Certs

I'm having an issue with linked Resources in Flash Builder. I work in a team environment where we use Linked Resources extensively. We just started developing ANEs and noticed that while linkedResources are used in the libraryPathEntry, in the buildTargets like anePathEntry and airCertificatePath, the absolute path is stored. I tried editing the .actionScriptProperties files directly, modifying the buildtarget absolute paths to linked resource equivalents using the libraryPathEntry as a guide but FlashBuilder complained when loading the project.
Is there a way to get the buildTargets to respect linkedResources and not save the absolute path? I'm trying to avoid the draconian way where all developers must have the exact same directory structure.
Thanks!
Randy
My team had this exact problem and all attempts to fix it with relative paths or workspace macros (i.e. ${PROJECT_LOC}) failed. It seems as if the team in charge of Flash Builder neglected to support relative paths in these particular dialogs, despite them being supported elsewhere.
Here is what we have done to fix this problem. I am assuming you are on a Mac/Linux or the like. If not, the concept here can still be applied.
Most of our projects already have a "set up" bash script that contributors run when they get code. Inside of that script, we simply set up a couple of symbolic links from the user specific absolute path, to a new absolute path with a "common" user. The script first creates the directory if it does not exist, and then creates the symlinks.
sudo mkdir -p /Users/common/<project>/
sudo ln -f -h -s ~/path/to/certificate/dir /Users/common/<project>/certificates
Obviously you can use whatever you like and whatever makes sense for the common path.
Now, in your .actionScriptProperties file you can change the location pointed to by the provisingFile and airCertificatePath to this new common absolute path.
<buildTarget ... provisioningFile="/Users/common/<project>/certificates/provisionfile.mobileprovision" ... >
<airSettings airCertificatePath="/Users/common/<project>/certificates/cert.p12" ... >
We actually take this a step further (and I suspect you will need to also) and create common symlink paths for the ANE files themselves. This ends up changing the anePathEntry to the common path as well.
<anePathEntry path="/Users/common/<project>/anes/some.ane"/>
You will need to make sure that you either hand edit the .actionScriptProperties file directly, or type in the fully qualified symlink path into the dialogs directly. Any attempt at using the Finder dialog launched by Flash Builder to navigate to the files in the common location resulted in the symlinks being auto-resolved to their actual locations.
The script requires sudo, which as I'm sure you know, will require that the users of it know their root password. Maybe some more bash savvy folks can suggest a way around sudo if this is not an option for you.
This will work for android stuff as well I believe. I don't know if that matters to you or not.
Hope this helps!
It looks like this issue was called out in the Flash Builder 4.6 known issues:
http://helpx.adobe.com/flash-builder/kb/flash-builder-4-6-known.html
https://bugs.adobe.com/jira/browse/FB-32955
The bug is apparently fixed but I haven't been able to check the new Flash Builder 4.7 beta yet:
http://blogs.adobe.com/flex/2012/08/flash-builder-4-7-beta-is-here.html