Lesson 15: Dev Processes & Tools¶
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Code Analysis¶
Code analysis tools are some of the most important tools in a developer’s arsenal when it comes to finding and fixing bugs. Code analysis tools come in two flavors:
Debugging Tools¶
Debuggers are interactive dynamic analysis tools that are used to inspect your code as it runs.
- Print (broken) variables.
- Read and reports error messages.
- Highlight (incorrect) syntax.
CLI Debugging Tools¶
C/C++ Tools
GDB
Valgrind
Python Tools
PDB
NodeJS Tools
node debug
Node Inspector
Linters¶
Linters inspect your code and flags suspicious usage. This can be to enforce a style guide or to flag code which will probably not compile or break the program when it is running.
- Examples:
- flake8 (Python)
- rubocop (Ruby)
- splint (C)
- jshint (NodeJS)
src/times.js: line 407, col 20, Expected '{' and instead saw 'return'.
src/times.js: line 415, col 49, Missing semicolon.
src/times.js: line 407, col 58, 'error' is not defined.
Code Coverage¶
Name Stmts Miss Cover Missing
-------------------------------------------------------
my_program.py 20 4 80% 33-35, 39
my_other_module.py 56 6 89% 17-23
-------------------------------------------------------
TOTAL 76 10 87%
Integrated Development Environments (IDE)¶
IDEs are programs used to help developers get their job done by integrating many essential tools into one ecosystem.
- Examples:
- Netbeans (Java)
- Visual Studio (.NET)
- PyCharm (Python)
- Eclipse (Many)
- Atom (Many)
Style Guides¶
Example: Real-World Style Guides¶
The Linux kernel style guidelines are actually fun to read:
“First off, I’d suggest printing out a copy of the GNU coding standards, and NOT read it. Burn them, it’s a great symbolic gesture.”
NASA’s Jet Propulsion Laboratory style guidelines are very short and are concerned with automated tooling to do code analysis:
“All loops shall have a statically determinable upper-bound on the maximum number of loop iterations.”
Dependency Isolation¶
Dependency isolation is the process of – wait for it – isolating the dependencies of a project. This is a surprisingly hard problem and many consider it largely unsolved.
TODO: Python Virtualenvs¶
Setup and enter the virtual environment.
$ virtualenv <virtualenv name>
New python executable in /path/to/<venv name>/bin/python
Installing setuptools, pip, wheel...
done.
$ source <venv name>/bin/activate
Install a package. This installs it in the current working directory and so does not ask for root permissions.
(<venv name>) $ pip install flask
[...]
To list all packages in the venv:
(<venv name>) $ pip freeze
click==6.7
Flask==1.0.2
itsdangerous==0.24
Jinja2==2.10
MarkupSafe==1.0
Werkzeug==0.14.1
Deactivate (leave) the venv.
(<venv name>) $ deactivate
$
Other Examples¶
- Node.js:
- Creates a node_modules directory and tracks dependencies in package.json.
- Go:
- Dependencies are tracked via git repositories and using the go get command.
- Rust:
- Dependencies and versions are specified in Cargo.toml. All compiled code (and dependencies) are stored in a target directory.
Development Servers¶
A Carbon Copy of the Production Environment(s)
Development servers are used to test that your code works in a real environment, with a real server, and real data. You shouldn’t throw your code up on a production website to see if it works, so a development server is as close to the real thing as you can get.
Further Reading¶
- The Community Ruby Style Guide is a good resource for anybody learning Ruby. It’s the style guide that Rubocop enforces.
- The Official Python Style Guide (PEP8) is a well respected style guide for Python and is commonly accepted as the python style guide.