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AX_EXPAND_PREFIX
When $prefix and $exec_prefix are still set to NONE then set them to the usual default values - being based on $ac_default_prefix. - this macro can be AC_REQUIREd by other macros that need to compute values for installation directories. It has been observed that it was done wrong over and over again, so this is a bit more safe to do.
remember - setting exec_prefix=’${prefix}’ needs you interpolate directories multiple times, it is not sufficient to just say MYVAR="${datadir}/putter" but you do have to run ‘eval‘ a few times, sth. like MYVAR=‘eval "echo \"$MYVAR\""‘ done at least two times.
The implementation of this macro simply picks up the lines that would be run at the start of AC_OUTPUT anyway to set the prefix/exec_prefix defaults. Between AC_INIT and the first command to AC_REQUIRE this macro you can set the two variables to something explicit instead. Probably, any command to compute installation directories should be run _after_ AM_INIT_AUTOMAKE
Download the latest version of ax_expand_prefix.m4 or browse the macro’s revision history.
Copyright © 2008 Guido U. Draheim guidod@gmx.de
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