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authorErlang/OTP <[email protected]>2010-04-23 04:32:51 +0000
committerErlang/OTP <[email protected]>2010-04-23 04:32:51 +0000
commitc725744dc889d43a66883ac54b778fca2083a2b4 (patch)
treec5c03b58be9db2832df98797d615300a048d92d5 /system/doc/reference_manual
parent280317139a17259fd7bf1dd8bbc95bee52c053b0 (diff)
parent45c380d1b77198449fb8e3beadb39dc8f77abb72 (diff)
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Merge branch 'ta/nested-records' into dev
* ta/nested-records: Document R14 paren-less record access/update Support nested record field access without parentheses OTP-8597 ta/nested-records Nested records can now be accessed without parenthesis. See the Reference Manual for examples. (Thanks to YAMASHINA Hio and Tuncer Ayaz.)
Diffstat (limited to 'system/doc/reference_manual')
-rw-r--r--system/doc/reference_manual/records.xml29
1 files changed, 26 insertions, 3 deletions
diff --git a/system/doc/reference_manual/records.xml b/system/doc/reference_manual/records.xml
index e2fe5fe8de..d01d883ef3 100644
--- a/system/doc/reference_manual/records.xml
+++ b/system/doc/reference_manual/records.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>2003</year><year>2009</year>
+ <year>2003</year><year>2010</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -13,12 +13,12 @@
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
-
+
Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
the License for the specific language governing rights and limitations
under the License.
-
+
</legalnotice>
<title>Records</title>
@@ -145,6 +145,29 @@ is_person(_P) ->
</section>
<section>
+ <title>Nested records</title>
+ <p>Beginning with R14 parentheses when accessing or updating nested
+ records can be omitted. Assuming we have the following record
+ definitions:</p>
+ <pre>
+-record(nrec0, {name = "nested0"}).
+-record(nrec1, {name = "nested1", nrec0=#nrec0{}}).
+-record(nrec2, {name = "nested2", nrec1=#nrec1{}}).
+
+N2 = #nrec2{},
+ </pre>
+ <p>Before R14 you would have needed to use parentheses as following:</p>
+ <pre>
+"nested0" = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0.name,
+N0n = ((N2#nrec2.nrec1)#nrec1.nrec0)#nrec0{name = "nested0a"},
+ </pre>
+ <p>Since R14 you can also write:</p>
+ <pre>
+"nested0" = N2#nrec2.nrec1#nrec1.nrec0#nrec0.name,
+N0n = N2#nrec2.nrec1#nrec1.nrec0#nrec0{name = "nested0a"},</pre>
+ </section>
+
+ <section>
<title>Internal Representation of Records</title>
<p>Record expressions are translated to tuple expressions during
compilation. A record defined as</p>