Copyright © 2001-2005 Oren Ben-Kiki, Clark Evans, Brian Ingerson
Status
This specification is a draft reflecting consensus reached by members of the yaml-core mailing list. Any questions regarding this draft should be raised on this list.
URI:
tag:yaml.org,2002:merge
Shorthand:
!!merge
Kind:
Scalar.
Canonical:
N/A (single format).
Regexp:
<<
Definition:
Specify one or more mappings to be merged with the current one.
The “<<” merge key is
used to indicate that all the keys of one or more specified maps
should be inserted into the current map. If the value associated
with the key is a single mapping node, each of its key/value pairs
is inserted into the current mapping, unless the key already exists
in it. If the value associated with the merge key is a sequence,
then this sequence is expected to contain mapping nodes and each
of these nodes is merged in turn according to its order in the
sequence. Keys in mapping nodes earlier in the sequence override
keys specified in later mapping nodes.
Example 1. !!merge Examples
---
- &CENTER { x: 1, y: 2 }
- &LEFT { x: 0, y: 2 }
- &BIG { r: 10 }
- &SMALL { r: 1 }
# All the following maps are equal:
- # Explicit keys
x: 1
y: 2
r: 10
label: center/big
- # Merge one map
<< : *CENTER
r: 10
label: center/big
- # Merge multiple maps
<< : [ *CENTER, *BIG ]
label: center/big
- # Override
<< : [ *BIG, *LEFT, *SMALL ]
x: 1
label: center/big