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Diffstat (limited to 'bitbake/doc/manual/usermanual.xml')
| -rw-r--r-- | bitbake/doc/manual/usermanual.xml | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/bitbake/doc/manual/usermanual.xml b/bitbake/doc/manual/usermanual.xml index cdd05998a5..c3403449fe 100644 --- a/bitbake/doc/manual/usermanual.xml +++ b/bitbake/doc/manual/usermanual.xml | |||
| @@ -89,6 +89,11 @@ share common metadata between many packages.</para></listitem> | |||
| 89 | <para>This results in <varname>A</varname> containing <literal>aval</literal> and <varname>B</varname> containing <literal>preavalpost</literal>.</para> | 89 | <para>This results in <varname>A</varname> containing <literal>aval</literal> and <varname>B</varname> containing <literal>preavalpost</literal>.</para> |
| 90 | </section> | 90 | </section> |
| 91 | <section> | 91 | <section> |
| 92 | <title>Setting a default value (?=)</title> | ||
| 93 | <para><screen><varname>A</varname> ?= "aval"</screen></para> | ||
| 94 | <para>If <varname>A</varname> is set before the above is called, it will retain it's previous value. If <varname>A</varname> is unset prior to the above call, <varname>A</varname> will be set to <literal>aval</literal>.</para> | ||
| 95 | </section> | ||
| 96 | <section> | ||
| 92 | <title>Immediate variable expansion (:=)</title> | 97 | <title>Immediate variable expansion (:=)</title> |
| 93 | <para>:= results in a variable's contents being expanded immediately, rather than when the variable is actually used.</para> | 98 | <para>:= results in a variable's contents being expanded immediately, rather than when the variable is actually used.</para> |
| 94 | <para><screen><varname>T</varname> = "123" | 99 | <para><screen><varname>T</varname> = "123" |