PYYAML Constructor

content/posts/easy-yaml-include-tag.md

@@ -1,6 +1,46 @@
 ---
 title: "Easy pyyaml '!include' Tag"
 date: 2020-04-28T20:59:26+02:00
-draft: true
 ---
 
+# Easy pyymal file inclusion
+
+YAML does not support file inclusion. If this feature is needed, it is necessary to write your own constructor to support a new tag like `!include`.
+
+## Example YAML files
+
+**foo.yaml:**
+```yaml
+hello: !include bar.yaml
+```
+
+**bar.yaml:**
+```yaml
+'world'
+```
+
+**resulting yaml:**
+```yaml
+hello: 'world'
+```
+
+## Example code
+
+```python
+import yaml
+
+
+def include_constructor(loader, node):
+    filename = node.value
+    include = yaml.load(open(filename, 'r'), Loader=yaml.SafeLoader)
+    return include
+
+
+Loader = yaml.CLoader
+Loader.add_constructor(u'!include', include_constructor)
+
+
+yaml_data = yaml.load(open('foo.yaml', 'r'), Loader=yaml.CLoader)
+```
+
+KTHXBYE.