layout: post title: Use Jinja to create gazebo sdf files categories: gazebo tags: [vscode, gazebo, jinja, sdf]
Jinja 101
Jinja2 is a template engine
Install
pip install Jinja2
Syntax
{{ }} Print and Evaluate an expression
{% %} Statement
{# #} Comments
Set variable
{% set title='hello world' %}
{{ title }}
Control
- for loop
{% set names = ['a', 'b', 'c']%}
{% for name in names %}
{{ loop.index }}: {{name}}
{% endfor %}
# Output result
1: a
2: b
3: c
| Variable | Desc |
|---|---|
| loop.index | index loop start with 1 |
| loop.index0 | index loop |
- if statment
{% set name='' %}
{% if name %}
{{ name }}
{% else %}
no name enter
{% endif %}
White space control
use + and - are control whitespace
- Run the loop example with hyphen at the end of line
{% set names = ['a', 'b', 'c'] -%}
{% for name in names -%}
{{ loop.index }}: {{name}}
{% endfor -%}
# same output without line spaces
1: a
2: b
3: c
Macro
{%- macro box(x, y, z) -%}
<geometry>
<box>
<size>{{x}} {{y}} {{z}}</size>
</box>
</geometry>
{%- endmacro -%}
# Call the macro
{{ box(1,1,1) }}
CLI for Jinja2
A CLI interface to Jinja2
- install
sudo pip install jinja2-cli
- usage
Usage: jinja2 [options] <input template> <input data>
Demos
- Template
{% if foo is defined -%}
foo difined and has value: define {{ foo }}
{% endif -%}
- Test
jinja2 -D foo=foo_value hello.txt.jinja
# result
foo difined and has value: define foo_value
Tips
- Install vscode ext for better syntax color
