codegen2

Simple code generator framework based on Python and Jinja2.

Requirements

Make sure the following packages are installed in your environment.

• argparse
• jinja2

Clone this repository using git clone, then make sure the codegen.py file is executable.

chown +x codegen2.py

Command Line Use

./codegen2.py --workdir=/some/directory --model=some_model.cgmdl

Note that the model file is relative to the workdir location. The model file extension is not constrained, however it is good practice to use a distinct extension, for example: .cgmdl

Model file

The model file is essentialy a Python source file, which is loaded dynamically during runtime. There are two constraints with this file:

1. It MUST include a dictionary named generators
2. It MUST include a dictionary names variables

Otherwise the model file could include any other Python code related to code generation. Typically the additional code would programmatically create or alter the generators or variables variables.

IDE Use

The main design consideration with the framework was to be able to work with IDE-s by running the generation automatically (similar to compiling CoffeeScript, SASS, and similar files).

JetBrain

In the JetBrain environments (IntelliJ IDEA, PyCharm, etc) there is a File Watchers plug-in that can watch specific files in a project and run any external tool when such file is created, or changed.

1. Setup a new file type
   1. Open Preferences > IDE Settings > File Types
   2. Add new File type: codegen2 Model file
   3. Register new patterns: ** *.cgmdl **
2. Create a new File Watcher
   1. Open Preferences > Project Settings > File Watchers
   2. Add a new File Watcher, Name: codegen2, check Immediate file synchroniation, select File type: codegen2 Model file, set Scope to Project Files, browse for the codegen2.py for Program, Arguments: --model=$FileName$ --workdir=$FileDir$

Once a new .cgmdl file is created, or modified the code generator runs and generates the files.

Eclipse

TODO

Example 1

This is a very-very simple example to show the basic use of the framework and artefacts.

example1.cgmdl

generators = {
    'test.py.template': 'test.py'
}
variables = {
    'greeting': 'Hello'
}

test.py.template

#!/usr/bin/python
print("{{greeting}} World!")

Running the generator produces the test.py file

#!/usr/bin/python
print("Hello World!")

Example 2

In this example one of the variables' value is dynamically set.

example2.cgmdl

generators = {
    'request.py.template': 'request.py',
    'response.py.template': 'response.py'
}

def who():
    return 'World'

variables = {
    'greeting': 'Hello',
    'subject': who()
}

request.py.template

#!/usr/bin/python
print('{{greeting}} {{subject}}!')

response.py.template

#!/usr/bin/python
print('{{greeting}} back!')

Running the generator produces the request.py file

#!/usr/bin/python
print("Hello World!")

and response.py file.

#!/usr/bin/python
print("Hello back!")

Values for the generators variable could be set dynamically similarly to the variables element in the example.