depz 0.0.4

Command line tool for symlinking directories with reusable code into the project

depz

Command line tool for symlinking directories with reusable source code into the project.

Language-agnostic.

Why

Reusing code should be simple. If I have the needed code in a directory on a local drive, I just want to include it into the project. Without packaging it as a library for distribution or messing with IDE settings.

My first thought is to create a symlink:

$ ln -s /abc/libs/mylib /abc/project/mylib

Now project sees mylib as a local directory project/mylib. I can edit both project and mylib while working on project.

But here problems arise:

• Portability. How to make the symlinks easy to recreate on another system?
• Recursive local dependencies. How to include not only mylib, but all the dependencies of mylib?

The answer is depz. It reduces these tasks to a one-line command.

Install

Get a working Python ≥3.7 and pip. You may also need a computer. Then:

$ pip3 install depz

Make sure that it is installed:

$ depz --help

Use

• Specify dependencies in depz.txt
• Run the command depz

Specify dependencies

File xxx/depz.txt lists dependencies for xxx:

• /abc/myproject/depz.txt for myproject
• /abc/libs/mylib/depz.txt for mylib

The depz.txt format:

# lines prefixed by hashes are ignored

# lines that specify local directory 
# names are LOCAL dependencies:

/absolute/path/to/mylib1
../libs/mylib2
~/path/mylib3

# lines that cannot be resolved to an existing 
# directory are considered EXTERNAL dependencies

requests
numpy

Run

$ cd /abc/myproject
$ depz

This recursively scans /abc/myproject/depz.txt and prints all the found dependencies. Does not write anything.

---

$ cd /abc/myproject
$ depz --relink

Removes all the symlinks found in /abc/myproject. Adds new symlinks to the local dependencies. Prints external dependencies.

Local dependencies

They are recursive

When a project depends on local mylib, it means, it also depends on all the dependencies of mylib. So after scannig myproject/depz.txt we will also scan mylib/depz.txt to include it's dependencies too.

Paths are relative to the current depz.txt

When we scan /abc/myproject/depz.txt, the paths are relative to /abc/myproject. Then we found a link to mylib and started scanning /abc/mylib/depz.txt. The paths found there are relative to /abc/mylib/depz.txt.

But all the symlinks will go directly into /abc/myproject.

The following examples show how the directories will be linked when running depz for /abc/project:

Default behavior

File	Line	Resolves to	Creates symlink
/abc/project/depz.txt	/abc/libs/xxx	/abc/libs/xxx	/abc/project/xxx
/abc/project/depz.txt	../libs/xxx	/abc/libs/xxx	/abc/project/xxx
/abc/libs/xxx/depz.txt	../zzz	/abc/libs/zzz	/abc/project/zzz

With --mode=layout

Useful for frameworks with strict directory structure.

File	Line	Resolves to	Creates symlink
/abc/project/depz.txt	/abc/libs/xxx	/abc/libs/xxx/src /abc/libs/xxx/test	/abc/project/src/xxx /abc/project/test/xxx
/abc/project/depz.txt	../libs/xxx	/abc/libs/xxx/src /abc/libs/xxx/test	/abc/project/src/xxx /abc/project/test/xxx
/abc/libs/xxx/depz.txt	../zzz	/abc/libs/zzz/src /abc/libs/zzz/test	/abc/project/src/zzz /abc/project/test/zzz

External dependencies

By default, the list of all external dependencies is simply printed to the terminal like that:

$ depz

Scanning /abc/myproject/depz.txt
...
External dependencies: pandas numpy requests

The -e argument causes the command to print only the list of dependencies.

Print in one line:

$ depz -e line

pandas numpy requests

This can be useful for installing Python external depedencies:

$ pip3 install $(depz -e line)

Or install external dependencies and symlink local ones:

$ pip3 install $(depz -e line --relink)

Print one per line:

$ depz -e multi

pandas
numpy
requests

Sample usage for creating pip-compatible file:

$ depz -e multi > requirements.txt