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| -rw-r--r-- | docs/gettingstarted/developers/vlib.md | 48 |
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diff --git a/docs/gettingstarted/developers/vlib.md b/docs/gettingstarted/developers/vlib.md index 13844ab455a..59206e5ed4b 100644 --- a/docs/gettingstarted/developers/vlib.md +++ b/docs/gettingstarted/developers/vlib.md @@ -540,6 +540,54 @@ certain cli command has the potential to hurt packet processing performance by running for too long, do the work incrementally in a process node. The client can wait. +### Macro expansion + +The vpp debug CLI engine includes a recursive macro expander. This +is quite useful for factoring out address and/or interface name +specifics: + +``` + define ip1 192.168.1.1/24 + define ip2 192.168.2.1/24 + define iface1 GigabitEthernet3/0/0 + define iface2 loop1 + + set int ip address $iface1 $ip1 + set int ip address $iface2 $(ip2) + + undefine ip1 + undefine ip2 + undefine iface1 + undefine iface2 +``` + +Each socket (or telnet) debug CLI session has its own macro +tables. All debug CLI sessions which use CLI_INBAND binary API +messages share a single table. + +The macro expander recognizes circular defintions: + +``` + define foo \$(bar) + define bar \$(mumble) + define mumble \$(foo) +``` + +At 8 levels of recursion, the macro expander throws up its hands and +replies "CIRCULAR." + +### Macro-related debug CLI commands + +In addition to the "define" and "undefine" debug CLI commands, use +"show macro [noevaluate]" to dump the macro table. The "echo" debug +CLI command will evaluate and print its argument: + +``` + vpp# define foo This\ Is\ Foo + vpp# echo $foo + This Is Foo +``` + Handing off buffers between threads ----------------------------------- |